MacOS Sierra: The smart person's guide. A cheat sheet; For this release, Apple opted to rebrand the OS X moniker and upgrade the OS feature set to include a number of productivity-enhancing. Apple previewed macOS High Sierra on June 5, 2017, the latest version of the world’s most advanced desktop operating system, delivering new core storage, video, and graphics technologies that pave the way for future innovation on the Mac. MacOS High Sierra offers an all-new file system, support for High-Efficiency Video Coding (HEVC) and an update to Metal, Apple’s advanced graphics.
A version of the macOS operating system | |
Developer | Apple Inc. |
---|---|
OS family | |
Source model | Closed, with open source components |
Initial release | September 25, 2017; 22 months ago |
Latest release | 10.13.6 (17G8030)[1](July 29, 2019; 25 days ago)[±] |
Update method | Mac App Store |
Platforms | x86-64 |
Kernel type | Hybrid (XNU) |
License | APSL and Apple EULA and Non-Disclosure Agreement |
Preceded by | macOS 10.12 Sierra |
Succeeded by | macOS 10.14 Mojave |
Official website | macOS High Sierra at the Wayback Machine (archived September 11, 2018) |
Support status | |
Partially supported. Extended support ends in September 2020. iTunes, in August 2021 |
Part of a series on |
macOS |
---|
|
- Selected Mac OS X Applications trash icon, or press Delete to delete a file. Using the Desktop The Apple menu: The Apple menu is your Mac’s control center. Use the Apple menu to open System Preferences, change the way the Dock works, or select a network location. You can also get new software, shut down and restart your computer, and log out.
- Macintosh Mac OS X Installer USB - Mojave,High Sierra,Sierra,El Capitan,Yosemite. Mac OS X El Capitan Quick Reference (Cheat Sheet of Keyboard Shortcuts + Notes.
macOS High Sierra (version 10.13) is the fourteenth major release of macOS, Apple Inc.'s desktop operating system for Macintosh computers. It is the successor to macOS Sierra and it was announced at the WWDC 2017 on June 5, 2017 before being released on September 25, 2017; its successor macOS Mojave was released on September 24, 2018.[2]
The name 'High Sierra' refers to the High Sierra region in California. As with Snow Leopard, Mountain Lion and El Capitan, the name also alludes to its status as a refinement of its predecessor, focused on performance improvements and technical updates rather than user features. Among the apps with notable changes are Photos and Safari.[2][3][4]
- 2Changes
- 2.1System
- 2.2Applications
- 3Reception
System requirements[edit]
macOS High Sierra runs on the following Macintosh computers:[5]
- iMac: Late 2009 or later
- MacBook: Late 2009 or later
- MacBook Pro: Mid 2010 or later
- MacBook Air: Late 2010 or later
- Mac Mini: Mid 2010 or later
- Mac Pro: Mid 2010 or later
macOS High Sierra requires at least 2 GB of RAM and 14.3 GB of available disk space.
HEVC hardware acceleration requires a Mac with a sixth-generation Intel processor or newer:
- iMac: Late 2015 27' or later, Mid 2017 21.5' or newer
- MacBook: Early 2015 or later
- MacBook Pro: Mid 2016 or later
External graphics processor support requires a Thunderbolt 3-enabled Mac:
- MacBook Pro: Late 2016 or later
- iMac: Mid 2017 or later
Changes[edit]
System[edit]
Apple File System[edit]
Apple File System (APFS) replaces HFS Plus as the default file system in macOS for the first time with High Sierra.[2] It supports 64‑bit inode numbers, is designed for flash memory, and is designed to speed up common tasks like duplicating a file and finding the size of a folder's contents. It also has built‑in encryption, crash‑safe protections, and simplified data backup on the go.[6]
Metal 2[edit]
Metal, Apple's low-level graphics API, has been updated to Metal 2. It includes virtual-reality and machine-learning features, as well as support for external GPUs.[2] The system's windowing system, Quartz Compositor, supports Metal 2.
Media[edit]
macOS High Sierra adds support for High Efficiency Video Coding (HEVC), with hardware acceleration where available, as well as support for High Efficiency Image File Format (HEIF). Macs with the Intel Kaby Lake processor offer hardware support for Main 10 profile 10-bit hardware decoding, those with the Intel Skylake processor support Main profile 8-bit hardware decoding, and those with AMD Radeon 400 series graphics also support full HEVC decoding [2]. However, whenever an Intel IGP is present, the frameworks will only direct requests to Intel IGP. In addition, audio codecs FLAC and Opus are also supported, but not in iTunes.[7][8]
Other[edit]
Kernel extensions ('kexts') will require explicit approval by the user before being able to run.[9]
The Low Battery notification and its icon were replaced by a flatter modern look.[citation needed]
The time service ntpd was replaced with timed for the time synchronisation.[10]
The FTP and telnet command line programs were removed.[11]
The screen can now be locked using the shortcut Cmd+Ctrl+Q. The ability to lock screen using a menu bar shortcut activated in Keychain Access preferences has now been removed.[12]
The 10.13.4 update added support for external graphics processors for Macs equipped with Thunderbolt 3 ports.[13] The update discontinued support for external graphics processors in 2015 or older Macs, equipped with Thunderbolt 1 and 2 ports.
Starting with 10.13.4, when a 32-bit app is opened, users get a one-time warning about its future incompatibility with the macOS operating system.[14]
Applications[edit]
Photos[edit]
macOS High Sierra gives Photos an updated sidebar and new editing tools.[2]Photos synchronizes tagged People with iOS 11.[2]
Mail[edit]
Mail has improved Spotlight search with Top Hits.[2] Mail also uses 35% less storage space due to optimizations, and Mail's compose window can now be used in split-screen mode.[15]
Safari[edit]
Safari has a new 'Intelligent Tracking Prevention' feature that uses machine learning to block third parties from tracking the user's actions.[16] Safari can also block autoplaying videos from playing.[17][18] The 'Reader Mode' can be set to always-on.[19] Safari 11 also supports WebAssembly.[20]
![Mac Os High Sierra Manual Cheat Sheet Mac Os High Sierra Manual Cheat Sheet](https://www.loggly.com/wp-content/uploads/2014/10/mac-parsing-2-700x394.png)
Notes[edit]
The Notes app allows the user to add tables to a note.[21] A note can be pinned to the top of the list.[22]
Siri[edit]
Siri now uses a more natural and expressive voice. It also uses machine learning to understand the user better. Siri synchronizes information across iOS and Mac devices so the Siri experience is the same regardless of the product being used.[23]
Messages[edit]
The release of macOS High Sierra 10.13.5 (and iOS 11.4) introduced support for Messages in iCloud.[24] This feature allows messages to sync across all devices using the same iCloud account. When messages are deleted they are deleted on each device as well, and messages stored in the cloud do not take up local storage on the device anymore.[25] In order to use the feature, the user has to enable two-factor authentication for their Apple ID.[26]
Reception[edit]
Reception of macOS High Sierra was reportedly positive.[27][citation needed]
Problems[edit]
macOS High Sierra 10.13.0 and 10.13.1 have a critical[28] vulnerability that allowed an attacker to become a root user by not entering the password. This was fixed in the Security Update 2017-001 macOS High Sierra v10.13.1.[29]
When it was first launched, it was discovered[by whom?] that the process named 'WindowServer' had a memory leak, leading to much slower graphics performance and lagging animations, probably due to some last-minute changes in Metal 2. This was fixed in macOS 10.13.1.
macOS High Sierra 10.13.4 had an error that caused DisplayLink to stop working for external monitors. Only 1 monitor is able to be extended, if using 2 external monitors, they can only be mirrored. This also seems to be an issue with the beta version of Mojave.[citation needed]DisplayLink have said they are working with Apple to resolve the issues but as of the most recent[when?] macOS High Sierra update, the issue still persists.[30]
Releases[edit]
Previous release | Current release | Beta |
Version | Build | Date | Darwin | Notes | Standalone download |
---|---|---|---|---|---|
10.13 | 17A365 | September 25, 2017 | 17.0.0 | Original Mac App Store release About the security content of macOS High Sierra 10.13 | N/A |
17A405 | October 5, 2017 | About the security content of macOS High Sierra 10.13 Supplemental Update | macOS 10.13 Supplemental | ||
10.13.1 | 17B48 | October 31, 2017 | 17.2.0 | About the macOS High Sierra 10.13.1 Update About the security content of macOS High Sierra 10.13.1 | macOS High Sierra 10.13.1 update |
17B1002 | November 29, 2017 | About the security content of Security Update 2017-001 | Security Update 2017-001 macOS High Sierra v10.13.1 | ||
17B1003 | |||||
10.13.2 | 17C88 | December 6, 2017 | 17.3.0 | About the macOS High Sierra 10.13.2 Update About the security content of macOS High Sierra 10.13.2 | macOS High Sierra 10.13.2 Update macOS High Sierra 10.13.2 Combo Update |
17C89 | |||||
17C205 | January 8, 2018 | About the security content of macOS High Sierra 10.13.2 Supplemental Update | macOS High Sierra 10.13.2 Supplemental | ||
17C2205 | |||||
10.13.3 | 17D47 | January 23, 2018 | 17.4.0 | About the macOS High Sierra 10.13.3 Update About the security content of macOS High Sierra 10.13.3 | macOS High Sierra 10.13.3 Update macOS High Sierra 10.13.3 Combo Update |
17D2047 | |||||
17D102 | February 19, 2018 | About the security content of macOS High Sierra 10.13.3 Supplemental Update | macOS High Sierra 10.13.3 Supplemental | ||
17D2102 | |||||
10.13.4 | 17E199 | March 29, 2018 | 17.5.0 | About the macOS High Sierra 10.13.4 Update About the security content of macOS High Sierra 10.13.4 | macOS High Sierra 10.13.4 Update macOS High Sierra 10.13.4 Combo Update |
17E202 | April 24, 2018 | About the security content of Security Update 2018-001 | Security Update 2018-001 macOS High Sierra v10.13.4 | ||
10.13.5 | 17F77 | June 1, 2018 | 17.6.0 | About the macOS High Sierra 10.13.5 Update About the security content of macOS High Sierra 10.13.5 | macOS High Sierra 10.13.5 Update macOS High Sierra 10.13.5 Combo Update |
10.13.6 | 17G65 | July 9, 2018 | 17.7.0 | About the macOS High Sierra 10.13.6 Update About the security content of macOS High Sierra 10.13.6 | macOS High Sierra 10.13.6 Update macOS High Sierra 10.13.6 Combo Update |
17G2208 | |||||
17G3025 | October 30, 2018 | About the security content of Security Update 2018-002 High Sierra | Security Update 2018-002 High Sierra | ||
17G4015 | December 5, 2018 | About the security content of Security Update 2018-003 High Sierra | Security Update 2018-003 High Sierra | ||
17G5019 | January 22, 2019 | About the security content of Security Update 2019-001 High Sierra | Security Update 2019-001 High Sierra | ||
March 25, 2019 | About the security content of Security Update 2019-002 High Sierra | Security Update 2019-002 High Sierra | |||
17G6030 | March 29, 2019 | About the security content of Security Update 2019-002 High Sierra | Security Update 2019-002 High Sierra | ||
17G7024 | May 13, 2019 | About the security content of Security Update 2019-003 High Sierra | Security Update 2019-003 High Sierra | ||
July 22, 2019 | About the security content of Security Update 2019-004 High Sierra | ||||
17G8030 | July 29, 2019 | About the security content of Security Update 2019-004 High Sierra | Security Update 2019-004 High Sierra |
References[edit]
- ^'About the security content of macOS Mojave 10.14.6, Security Update 2019-004 High Sierra, Security Update 2019-004 Sierra'. Apple Support. July 29, 2019. Retrieved July 30, 2019.
- ^ abcdefgh'Apple Events - WWDC Keynote, June 2017 - Apple'. Archived from the original on 2017-06-06.
- ^'MacOS 10.13 High Sierra Announced, Release Date Set for Fall'. OS X Daily. Archived from the original on 27 June 2017. Retrieved 6 June 2017.
- ^Cunningham, Andrew. 'macOS High Sierra tech preview: A quick look at the stuff you can't see'. Ars Technica. Archived from the original on 20 June 2017. Retrieved 20 June 2017.
- ^'How to download macOS High Sierra'. Apple Inc.
- ^'Apple File System (APFS) announced for 2017, scales 'from Apple Watch to Mac Pro' and focuses on encryption'. 9to5Mac. 2016-06-13. Archived from the original on 2017-03-28. Retrieved 2017-09-12.
- ^iOS 11、macOS High Sierra:FLAC、Opus、HOA(3Dサウンド)をサポート | NEWS | Macお宝鑑定団 blog(羅針盤)Archived 2017-09-14 at the Wayback Machine
- ^What's New in Audio - WWDC 2017 - Videos - Apple DeveloperArchived 2017-09-14 at the Wayback Machine
- ^'Secure Kernel Extension Loading'. Apple Developer. June 19, 2017. Retrieved June 24, 2017.
- ^'Has anyone got the time? How High Sierra has changed time synchronisation'.
- ^'How to get BSD FTP and Telnet back in 10.13 (High Sierra)?'. Ask Different.
- ^'New Lock Screen feature in macOS High Sierra'. July 17, 2017.
- ^'Use an external graphics processor with your Mac'. Apple.
- ^'32-bit app compatibility with macOS High Sierra 10.13.4 - Apple Support'. April 11, 2018.
- ^'macOS High Sierra: Everything We Know | MacRumors'. Archived from the original on 2017-06-17. Retrieved 2017-09-11.
- ^Lomas, Natasha. 'Apple adds ad tracker blocker to desktop Safari | TechCrunch'. Archived from the original on 2017-06-07. Retrieved 2017-06-07.
- ^O'Kane, Sean (2017-06-05). 'Apple's new version of macOS is called High Sierra'. The Verge. Archived from the original on 2017-06-07. Retrieved 2017-06-08.
- ^'macOS is now fully baked with macOS High Sierra'. Ars Technica. Archived from the original on 2017-06-07. Retrieved 2017-06-08.
- ^'5 Notable New Features Coming to macOS High Sierra'. OS X Daily. 2017-06-09. Archived from the original on 2017-06-27. Retrieved 2017-06-10.
- ^'What's New in Safari'. Archived from the original on 2017-11-14.
- ^'Apple Reveals 'macOS High Sierra' With APFS, Metal 2, and Refinements to Safari and Other Apps'. Archived from the original on 2017-06-06. Retrieved 2017-06-10.
- ^Gil, Lory (8 June 2017). 'macOS High Sierra FAQ: Everything you need to know!'. iMore. Archived from the original on 19 June 2017. Retrieved 20 June 2017.
- ^'macOS High Sierra: Everything We Know | MacRumors'. Archived from the original on 2017-06-17. Retrieved 2017-09-11.
- ^'Apple Releases macOS High Sierra 10.13.5 With Messages in iCloud Support'. MacRumors. 2018-06-01. Retrieved 2018-11-01.
- ^'iOS 11.4: What you need to know about Messages in iCloud'. CNET. 2018-05-29. Retrieved 2018-11-01.
- ^'How to sync your text messages to iCloud'. iMore. 2018-06-01. Retrieved 2018-11-01.
- ^'macOS High Sierra review: Incremental update worthy of your time, eventually'. Macworld. 2017-09-25. Retrieved 2018-11-01.
- ^'Vulnerability Details : CVE-2017-13872'.
- ^'macOS High Sierra 'root' security bug: Here's how to fix it now!'. iMore. Archived from the original on 2017-12-04. Retrieved 2017-12-06.
- ^'macOS High Sierra 10.13.4+ and Mojave 10.14 Early Previews'. DisplayLink Support.
External links[edit]
- Official website at the Wayback Machine (archived September 11, 2018)
Preceded by macOS 10.12 | macOS 10.13 2017 | Succeeded by macOS 10.14 |
Retrieved from 'https://en.wikipedia.org/w/index.php?title=MacOS_High_Sierra&oldid=912135181'
HomePlatformMacApple macOS High Sierra: A cheat sheet
With Excessive Sierra, model 10.13 of Apple’s macOS working system, the corporate added refined updates to enhance the privateness of net shopping in Safari, rolled out its new file system as commonplace, and launched updates that might permit for the creation of digital actuality (VR) and augmented actuality (AR) content material. Whereas the updates could seem easy, they assist set the stage for Apple’s method to computing sooner or later.
To assist tech leaders and IT professionals higher perceive macOS Excessive Sierra, we have put collectively a very powerful particulars and sources on this cheat sheet. This can be a “residing” article that will probably be up to date and refreshed as new, related data turns into public.
SEE: All of TechRepublic’s cheat sheets and smart person’s guides
Government abstract
- What’s macOS Excessive Sierra? macOS Excessive Sierra is model 10.13 of Apple’s desktop working system (OS) sequence, macOS. It builds on its predecessor, macOS Sierra, and contains updates to Safari, Mail, Photographs, its file system, and extra.
- Why does macOS Excessive Sierra matter? As a model of macOS, Excessive Sierra will outline the person expertise for Apple pc customers throughout laptops and desktops when it comes to featureset and UI.
- Who does macOS Excessive Sierra have an effect on? The launch of macOS Excessive Sierra impacts Mac customers and admins who’ve a suitable system and are planning on upgrading to the OS, or non-Mac customers who’re planning to buy an Apple pc sooner or later.
- When is macOS Excessive Sierra accessible? The primary macOS Excessive Sierra public beta got here out in June 2017, however the public launch of Excessive Sierra was made typically accessible on September 25, 2017.
- How do I reap the benefits of macOS Excessive Sierra? Excessive Sierra is obtainable for obtain by way of the Mac App Retailer.
SEE: Apple’s first employee: The remarkable odyssey of Bill Fernandez (PDF download) (TechRepublic)
What’s macOS Excessive Sierra?
Apple’s macOS 10.13 Excessive Sierra is the most recent Mac working system, designed to be used on iMac desktops and MacBook laptops. It was announced at the 2017 WWDC event in San Jose by Apple’s senior vice chairman of software program engineering, Craig Federighi.
One of many greatest updates unveiled with the Excessive Sierra macOS model is that the Apple net browser, Safari, will now block AutoPlay movies, so customers will not encounter movies mechanically taking part in once they open an online web page. Whereas the function will enhance the shopping expertise for a lot of customers, it’s going to make it more difficult for Apple to compete with promoting giants Google and Fb.
Excessive Sierra brings Clever Monitoring Prevention for Safari, a brand new function that blocks trackers of person knowledge. “Now your privateness, your shopping historical past is your individual,” Federighi mentioned at WWDC.
Mail search on Mac can be improved with Excessive Sierra, whereas Photographs obtained a brand new design and structure. Apple is thought for its picture options, equivalent to dwell pictures in iOS and content material administration choices in iCloud Drive, and Excessive Sierra affords higher facial recognition assist for improved group and extra.
Excessive-efficiency video coding (HEVC) H.265 will probably be supported by macOS Excessive Sierra. H.265 is a next-generation video compression commonplace that mainly permits video recordsdata of the identical high quality to be compressed to a smaller dimension. The usual can be supported on cellular beginning with iOS 11, which means the movies a person takes on their iPhone or iPad will stay top quality with out taking over as a lot area.
With the announcement of macOS Excessive Sierra, Federighi mentioned that the Apple File System (APFS) could be the default for all Macs transferring ahead. APFS permits macOS customers to extra simply handle area between a number of volumes, in that they’ll simply add and delete volumes on solid-state drives (SSDs) inside the Disk Utility.
“APFS-formatted volumes mechanically develop and shrink—you by no means must repartition an SSD drive once more,” an Apple support page mentioned. “To see the format of a quantity, choose it within the Disk Utility sidebar—its format is displayed beneath the quantity title in the course of the window.”
Steel 2, which makes it simpler to leverage GPU computing on a Mac, and can assist extra VR and AR content material, was additionally introduced as a part of macOS Excessive Sierra. Steel 2 affords exterior GPU assist as properly.
Further sources:
Why does macOS Excessive Sierra matter?
With an ever-increasing quantity of labor being executed on-line, the refinements to Safari in Excessive Sierra might assist place Macs as a extra viable enterprise machine for sure industries. Moreover, Apple boosted the browser’s pace. “Safari is the world’s quickest desktop browser with Excessive Sierra,” Federighi mentioned at WWDC.
The extra privateness measures will assist Safari—and, thus, Excessive Sierra—win over another customers as properly. New Safari Reader options will enhance the readability of some net pages and articles by eliminating advertisements and unrelated content material.
Within the Notes app, tables can now be added to make fast graphical representations of one thing a person is engaged on. Enterprise vacationers can monitor flights within the Highlight search window in Excessive Sierra, making for a extra environment friendly and productive course of.
Consistent with its fame as a powerhouse for creatives, Apple added some new options for its Photographs app. Improved facial recognition reveals that Apple is investing within the underlying applied sciences—like machine studying—that energy synthetic intelligence (AI), which is an space it has been lagging behind in relative to rivals like Google, Microsoft, and Amazon. In Excessive Sierra, Photographs will combine with different enhancing instruments like Photoshop and Pixelmator, which might assist draw extra creatives deeper into Apple’s proprietary ecosystem.
![Mac os versions Mac os versions](https://www.dummies.com/wp-content/uploads/sierra-desktop.jpg)
Excessive Sierra is Apple’s first main foray into AR and VR applied sciences. Steel 2 will make it simpler for customers to make the most of GPU compute, however it’s going to additionally assist VR content material creation—a primary for Macs. Unity, Epic, and SteamVR integrations, together with Remaining Lower Professional X assist for 360 video will assist entice the following technology of creatives to Apple machines.
Further sources:
Who does macOS Excessive Sierra have an effect on?
On a excessive stage, the debut of macOS Excessive Sierra issues to present Mac customers and anybody contemplating a Mac for his or her subsequent machine. Nevertheless, it has extra particular impacts for sure subsets of customers.
Inventive professionals can use the H.265 assist to stream 4K video, and cellular customers can leverage it to avoid wasting area on their iOS units, whereas the brand new Photographs app might assist increase environment friendly enhancing. Creatives trying to develop VR content material might leverage the brand new OS options to construct out their portfolio, too.
https://eversat354.weebly.com/change-mac-shell-manual.html. Builders will probably be affected by the the software program replace, as they’ll use Steel 2 to enhance utility improvement.
Safety-conscious customers will possible have an interest within the new privateness options in Safari, equivalent to AutoPlay blocking and Clever Monitoring Prevention. customers may see slight productiveness enhancements with the updates to Mail and Notes.
Further sources:
When is macOS Excessive Sierra accessible?
On June 5, 2017, Apple unveiled macOS Excessive Sierra for the primary time at WWDC. It’s only the second occasion of Apple’s use of the macOS moniker, which changed the earlier OS X title in 2016 when macOS Sierra was launched.
On the WWDC occasion, macOS Excessive Sierra was made accessible in beta. Apple launched macOS Excessive Sierra for normal obtain on September 25, 2017. Varied updates and patches have been launched since then to deal with safety points and add function enhancements.
It ought to be famous late 2017 security flaw in macOS Excessive Sierra reportedly gave attackers root person entry, until the person set a root password to guard the machine. A later 2018 bug in the Disk Utility revealed APFS-encrypted drive passwords in plain textual content, however this was patched in macOS Excessive Sierra model 10.13.four. Customers ought to replace to this model to keep away from this vulnerability. A direct hyperlink for the obtain might be discovered here, or customers can replace by way of the App Retailer.
Further sources:
How do I reap the benefits of macOS Excessive Sierra?
At present, macOS Excessive Sierra is obtainable within the Mac App Retailer, however it’s going to only run on certain Mac computers. customers with a suitable machine can obtain the OS right this moment.
https://eversat354.weebly.com/blog/mac-cosmetic-training-manual. Figuring out compatibility for the macOS replace begins with the mannequin pc a person at the moment has. Based on Apple’s website, the next machines are eligible to run macOS Excessive Sierra:
- iMac fashions from late 2009 or later
- MacBook fashions from late 2009 or later
- MacBook Professional fashions from mid 2010 or later
- MacBook Air fashions from late 2010 or later
- Mac mini fashions from mid 2010 or later
- Mac Professional fashions from mid 2010 or later
- iMac Professional
Mac Os High Sierra Manual Cheat Sheet 2017
If a person has one of many suitable fashions, in addition they must be working one of many following variations of Apple’s working system software program:
- macOS Sierra
- OS X El Capitan
- OS X Yosemite
- OS X Mavericks
- OS X Mountain Lion
To put in the replace, a person will want 2GB of free reminiscence and 14.3GB of storage accessible on their laborious drive area. Total, macOS Excessive Sierra requires roughly 1.5GB extra space for storing than macOS Sierra 10.12.6, Apple’s web site mentioned. The entire data on a Mac’s mannequin, reminiscence, storage, and OS model might be discovered underneath the About This Mac part within the Apple menu.
Further sources:
Related
Mac Os High Sierra Manual Cheat Sheet Music
Shop Amazon