Fast User Switching: A Windows 7 feature that allows you to quickly switch between users.

favicon: The small icon next to a URL address in an Internet browser's address bar.

file extension: A three- or four-digit suffix to a filename that tells Windows 7 what program should open the file.

Firefox: An Internet browser developed by Mozilla.

firewall: A software or hardware device designed to block unauthorized intruders from gaining entry to an individual computer or a network.

flash drive: A keychain-size storage unit that saves files on memory cards; you can plug it into your computer and access it like any other external hard drive.

Flip 3D: When the Aero color scheme is engaged, this tool allows you to visually scroll through all open applications.

folder: An operating system object that can contain multiple files and other folders.

font: The combination of typeface and other qualities, such as size, pitch, and spacing, that can be applied to characters in a document.

frozen: A state in which your PC does not respond to keyboard or mouse commands; also called locked or locked up.