About releases:

What is a release?

Original releases are rips of movies, programs, games and music, all released by groups specialized in creating these kinds of releases, so called releasegroups.
A release is the full package of a ripped game, movie etc. (more release types). These releases are all created in a standard way, according to the scene rules. That way the tag (directory name) and the included info file directly give you a lot of information about the release type, the source and so on. More about tags here.

First there is the actual content. Most big releases with the sice of a CD or DVD are released as a cd or dvd image, mostly in .ISO or .IMG format. Basically an image is a complete backup of a cd/dvd. They can be burned (Nero, Alcohol 120%) or mounted (Alcohol 120%, Daemon Tools). Apart from the actual content it's often packed into compressed files for easy spreading. Also it contains an info file which will tell the downloader all about what's in the release, how it's created and what the quality is. More about how a release looks like here.

To ensure the quality of a release, there are the scene rules which are set up by the releasegroups. These scene rules exactly tell how a release should be prepared for the scene. This is the big advantage of scene releases, you'll always get high quality. The whole scene system keeps it safe, clean, and ensures high quality only.