Firefox (and other browsers) have a special URI scheme to display internal pages, or built-in functions. These commands start with an "about:" followed something, for example - "about:blank" displays a blank page.
These commands can be quite handy sometimes. For example, yesterday, I was searching for how to use the "sync tabs" feature of Firefox 4 and 5. I knew how to enable tabs sync, but I did not know where I could access the synced tabs. Of course, if I had just gone through the menu, I would have found it under "History > Tabs from Other Computers". But, Firefox 4 and 5 have their menu bars hidden by default, and so I searched online and came upon another way to do that: just type "about:sync-tabs" in the address bar (without quotes), and there are your tabs.
So, I decided to find a list of all about: commands which can be used in Firefox. And I found some easter eggs among them. Here are the commands that I found to be working on my version of Firefox:
Shows a verse from the fictional Book of Mozilla.
Try it in your own browser, or see the screenshot below.
General Information Pages:
Shows information about Firefox.
Shows a blank page
Shows the Firefox home page with a Google search bar.
Shows the addons page
Shows tabs synced from other computers (tab syncing has to be enabled).
Shows the sync logs
Shows the Mozilla Public License.
Shows licensing information and your rights.
Shows the logo used on the about: screen.
Shows installed, currently enabled plug-ins.
Shows the arguments and options used to compile the Firefox build in use.
Shows information about the data in the browser cache.
Shows the disk cache device info, keys, and data.
Shows the memory cache device info, keys, and data.
Shows details of crashes submitted by Mozilla's crash reporter.
Shows memory usage.
Shows the firefox configuration page with a lot of configuration options.
Shows troubleshooting information.
Can be used to switch to private browsing mode.
Shows an interface for viewing about last session.
Shows the malware protection page used when the browser identifies a page as not safe for viewing.
Shows the error page used when an SSL/TLS certificate is untrusted or otherwise invalid.
Shows the page used when clicking the rss feed icon in the address bar.
Shows the error page used when the browser could not access the requested path.
Update : Check my new post for some more "about" commands.
If I missed something, you can let me know in the comments.
Also check :
- Some more Firefox about: commands
- Start Firefox in Safe Mode by holding down the Shift Key
- 20+ Google Chrome's about: and chrome:// commands
- View any Web Page in 3D with Firefox 11