A subtitle is the text at the bottom of the screen in a movie. The purpose of a subtitle is usually to translate the movie dialogue from a language the viewer doesn't understand to another. Subtitles can also be useful for people who for some reason have trouble following the dialogue in a movie. Personally, I mostly use them to watch movies that are originally in English (I prefer originals over translations, that are often inadequate), which is not my native language and it can be a problem for me to understand it sometimes by hearing only.
Watching DivX movies with subtitles
To watch DivX movies with subtitles you first need to install a directshow filter for Windows Media Player which is called DirectVobSub. To install DirectVobSub, follow these easy steps:
1) Download DirectVobSub
2) Run the exe-file to start the installation
After you've installed DirectVobSub on your computer, Windows Media Player will be able to show subtitles in DivX movies. However, you will also need to download a separate DivX subtitle file before you get subtitles in a movie. Once you've downloaded a subtitle for a movie you simply place it in the same folder as the DivX movie you want to watch. Then you have to make sure the filename of the movie and subtitle is the same. Otherwise you will have to rename the subtitle file, so the player understands that they are associated. Also make sure that the subtitle file has the ".sub" file-extension. Finally you start the movie and you should hopefully get subtitles when you watch the movie.
You can also use some third party player, that has built-in subtitles support. They exist in vast numbers. Most Popular third-party FREE player is: BS Player. Also, I recently tried MPlayer which was originally for Linux, but there is a Windows version as well. I found it attractive for two reasons - 1. It loads CPU 5 - 10 times less than Media Player. 2. It understands DVD subtitle format, which other players known to me don't. However it's somewhat buggy and complicated to configure and use. For advanced users only. If you wish to try it under Windows - grab Windows GUI version (another is a console version, not graphic). Another great free player which probably beats everything named before is GomPlayer
Be warned that divx movies come in a variety of formats and versions that often have different frame rate and length cut. And subtitle file may not match it. You can use Subtitle Workshop to convert the format yourself.