Different File Extensions

There are tons of different extensions out there, and here are some of the most common one's you're going to come across, and a little bit about them.

Compression Files

.rar .001 .zip .ace
These files make up one or more files that are compressed, so your download size is smaller. You can use WinRAR, PowerArchiver, WinZIP or WinACE to extract and read these files.

.cbr .cbz
These are usually compressed comic books, and you need CDisplay to open them.

Multimedia Files

.divx .xvid .wmv .avi .mpg .mpeg
This format usually holds video of some sort, mostly associated with files or TV shows, and there are many different players out there – VLC, BSPlayer, Winamp, DivX Player, Windows Media Player, and my favorite, Media Player Classic.

.ra .rm .ram
These are files that only work with RealPlayer. Some really like these, and some don't, but no matter – had a tendency to crash systems.

.mp3 .mp2
These are music files, and are there tons of different players that play them! Winamp and Media Player are the most common, but my favorite is Media Player Classic for it's simple design, and how easy it is to use.

.ogm .ogg
These are Ogg Vorbis media files that are actually music. You can use DirectShow Ogg filter to play the files, or the latest version of Winamp.

.vcd .svcd
This are called Video CD, or Super Video CD, and if they're burned to a disc, they'll play in almost any modern DVD player.

.mov
This file is only associated with Quicktime, and is a pain if you need to download it, because you have to download iTunes as well.

CD Image Files

.bin .cue .ccd .img .sub .iso
These are actual images of a CD, and they're extremely common. They're the exact replica of the CD they're supposed to be. There are a few programs you can use to burn these, but Nero is by far the most popular.

Programs like Alcohol 120% and Daemon Tools allow you to create a virtual drive, and you can mount the image on it, and then treat it like a regular CD or DVD.

.mds .mdf
These are what's called Media Descriptor Images, and you can use Daemon Tools or Alcohol 120% to mount them.

.nrg
These re images that are specific to Nero, and you have to use it to burn them.

Other Important File Extensions

.txt .doc .rtf
These all contain text, and you can open .txt using NotePad, .doc using Word or OpenOffice, and .rtf can be opened in either.

.pdf
You have to view these using a .pdf viewer like Adobe Acrobat Reader or Foxit Reader.

.nfo
These are information files, and you should always open them in NotePad and read them, when they're associated with something you've downloaded.