The Extension Repository is a central server in which every single published TYPO3 extension is stored. This makes the TER (TYPO3 Extension Repository) the central resource for all T3 extensions, whether they are plug-ins for use in the T3 Frontend or modules for the T3 Backend.
There are currently around 3400 extensions stored in the TER, ready for downloading, including so-called "shy extensions", or system extensions, which can also be downloaded, installed and uninstalled.
The extensions available in the TER are regularly updated, and, since TYPO3 version 4.0 was launched, also tested for security loopholes. The T3 Security Team tests the extensions and gives the appropriate warning if any possible security breach is found, although this is not a functional guarantee that the extension will run error free, or does what it says it does.
Nonetheless, before installing an extension, it is a good idea to consult the T3 Association's security warnings. These Security Bulletins can be found at: http://typo3.org/teams/security/security-bulletins/
Accessing the Extension Repository:
The Extension Repository can be reached in two ways:
- Via the typo3.org webpage, under: http://typo3.org/extensions/repository there is a list of all published extensions, which can be individually downloaded in the compressed T3X file format or ...
- Via the Extension Manager directly from the Backend.
The Extension Manager:
With the Extension Manager, TYPO3 provides a comfortable tool for the management and installation of any extensions installed on the system. It can also be used to download missing plug-ins or modules directly from the T3 Backend or to upload self-developed extensions into the TER. Such uploaded extensions are then available for download by any TYPO3 user, whether to install in their own website, to develop further, or to customize the code for their own requirements.
An introduction on how to download and install an extension using the Extension Manager can be found as a video file here: http://typo3.org/documentation/videos/xvid-format/#c2365
Further general information on how to work with the TER and the Extension Manager is available here: http://typo3.org/extensions/what-are-extensions/