Learning English with Audiovisual Language Techniques
If you are interested in more information about subtitling and dubbing practices, there are a couple of websites I can recommend. And of course, Google will always be your friend, there are plenty of websites and fora talking about this subject.
More on the differences between dubbing & subtitling and their history
Advantages and disadvantages of subtitling and dubbing
For any Spanish people who are interested here is an more extensive online course on subtitling which also includes some assignments on making subtitles yourself and reviewing them.