Flash is a ClosedSource vector graphics and animation plugin, made by 
Adobe (but formerly by Macromedia, which Adobe ate). It is the most common WebBrowser plugin, and is used in many commercial sites, even if only in advertisements. The version of Flash available for Linux in September 2006 is 7. Windows and Macs are onto version 9, so some sites will not work with Linux, even if you install the plugin. Version 9 for Linux is apparently due in 2007.
The SWF? file format used by Flash is not itself entirely closed, and from time to time people attempt to create a free player. Gnash is currently (9/2006) regarded as the leading candidate, and can reputed play some SWF files without crashing.
It is quite easy to create SWF content using free tools, such as Ming, SWFTools, and MTASC. The open source flash website is a useful resource if you are so inclined.
Many WebComics are done in MacromediaFlash.
Often there are font problems with Debian when using MacromediaFlash. Possibly Ubuntu might have the same issues also.
Edit the file /usr/X11R6/lib/X11/fs/config and make sure you have /var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType/ path listed in the catalogue line. Restart xfs (sudo /etc/init.d/xfs restart) and restart your web-browser.
(NB The reference to X11R6 is deliberate rather than xfree as this is where MacromediaFlash looks)
This information was originally found at http://www.linuxforums.org/forum/debian-linux-help/46720-flash-player-problem-2.html and then modified.
All flash websites work perfectly after following this guide:
http://ubuntuforums.org/showthread.php?t=341727
4 pages link to MacromediaFlash:
