AMO (addons.mozilla.org) is the main add-ons hosting site for Firefox and other Mozilla applications. Although you can distribute your add-ons on your own website, AMO provides free hosting and update services as long as you comply with their basic guidelines.
Updating icons and descriptions
Firefox 4 periodically asks AMO for updated information about all installed add-ons, and uses that information to update the information displayed in the Add-ons Manager panel. This means that you can change basic details about how your add-ons are presented without needing to update your add-on, by simply modifying the information using the AMO developer tools web site.
The following pieces of information are automatically updated:
Opting out of AMO updates
Sometimes you may not want your add-on to automatically update the information listed above from AMO, or you may prefer that Firefox not include your add-on in the list of installed add-ons that it sends to AMO. You can opt out of information updates on a per-add-on basis by simply including the following preference in one of your add-on's default preference files: