A new installation of Gentoo will typically not include a Flash plugin for your browser. I'm using Firefox. If you go to a site that has Flash content, Firefox asks you if you want to install the needed plugin. Clicking through, you get to the Adobe site, where you can download a *.gz file. Unfortunately, unpacking this file and following the instructions may not provide you with a working Flash player within Firefox.
This led me to search for a flash player using Gentoo's
emerge --search option. Executing:
emerge -s flash
returned a list of applications that included net-www/netscape-flash:
* net-www/netscape-flash Latest version available: 10.0.22.87 Latest version installed: [ Not Installed ] Size of files: 8,747 kB Homepage: http://www.adobe.com/ Description: Adobe Flash Player License: AdobeFlash-10
That indeed sounded like what I was looking for.
So, I "emerged" the application:
restarted Firefox, and: Voila! I now have a working Flash player in Firefox on Gentoo Linux.