Bet you can't guess what these series of books are all about, actually its a bit of a no brainer, thats right it is a bunch of stories set in the Star Wars(probably tm) universe. A long time ago........
This is a huge series of books, it is constantly growing and there are a large number of authors writing it. Basically anyone can write a story for the series provided that they don't contradict anything that has allready been published, the story is in keeping with the spirit of the Star Wars universe and probably has to pass some minimum quality standard. I would also like to think that each story adds something to the over all body of work.
As well as the books that are novelisations of the movies, there are stories from every concievable time period relative to the movies. Most of the books I currently have are based after Return of the Jedi, this is basically because they are ones that I have picked up cheap when they have been on a cheap pile or discount book shop. I fully intend to expand this collection . I have several Star Wars books sitting on the to read pile.
The beauty about the Star Wars novels is that it everything has a degree of familiarity to it from what we have seen in the various movies, yet at the same time there are all these new things, expanding the universe one story at a time. Hence the term Extended Universe
There are whole stories about favourite characters, other times they just make a cameo apearence only showing up to save the day.
Basically if you enjoyed the movies then I highly recomend reading some of the novels.