This is a great video that covers the topic of snippets very well in what I feel is an easy to understand format. This video also touches on the topic of sitelinks and how they are generated for sites. It is worth a view if you have 8 minutes to spare.
One thing I should mention is that the audio on this particular video is not the greatest in some parts. Everything is audible but there is a little static in a few places so don't make the mistake and think that your speakers are the problem.










