If you're new to Anki and not upgrading from a previous version, please jump straight to the downloading section below.
All Anki 1 users are encouraged to upgrade to Anki 2, as it brings a lot of improvements. Please have a look at the change notes before you upgrade, as they include information on how to prepare for the upgrade and a heads up about notable changes.
The upgrade process will automatically import your old decks, but leave them untouched. If you decide you wish to revert to the previous version of Anki, your old data will still be there.
The old AnkiWeb was shut down on Feb 7 2013. Anki 1 will no longer be able to sync, or download shared decks/plugins from within the program. This was not done to force users to upgrade, but simply because both the desktop and web versions are provided for free, and I do not have the time or resources to support two major versions at once. You are welcome to continue using Anki 1 if you choose not to upgrade for now, but if you wish to use it on multiple machines, you will need to manually move decks around or look into an alternative synchronization service like Dropbox instead.
You can log in to the new AnkiWeb using your old username and password. When you do this for the first time, AnkiWeb will import your 1.2 decks into the new system. This automatic upgrade is intended for people who primarily use the web interface and do not have any sound or images on their cards. If you use sounds or images on your cards, please download Anki 2 and upgrade via that, in order to ensure your decks are upgraded properly.
If you use Anki on an Android device, please see the dedicated AnkiDroid upgrade page before upgrading.
To download Anki 2, please click the link that matches your computer type:
Please note that if you're on Windows and using Norton Antivirus, it may misleadingly say that the download contains a virus. You can read more about this misguided behavior on this page, and you may want to consider something better and free in the future, like Microsoft Security Essentials.
Please also note that you won't be able to install the file if you're using Internet Explorer 9. IE9 claims the file is "not commonly downloaded" because Anki 2 was only released recently, and refuses to let you install it. You can either work around this misguided behavior, or use a better browser like Firefox or Chrome.
If you can't find what you need in the intro videos and manual, please post a question on the help forum.