If you have no idea why you should rename the episodes of your TV shows, take this example. Suppose you have the Prison Break TV series with its episodes named like this:
But it would be quite useful if you could have them renamed a little more descriptively like this:
Prison Break – 1×04 – Cute Poison.avi
Prison Break – 1×05 – English, Fitz or Percy.avi
Or you may need to rename them to another specific format.
FileBot is a free and open source tool which does this renaming for you automagically. It obtains the correct episode names from sites like TVRage and AniDB, so it will work for almost all TV shows and anime. Other than renaming shows, it has several other features, including subtitle downloads.
FileBot is cross-platform and can be launched via Java Web Start. The app is less documented and its features are a bit hidden, though.