Seems like lately I've either been asked about timelaps photography or I've seen questions on Flickr about it. I know when I did my first (like I've done a lot of them) one I looked for a good resources that talked about how to do them but I never really found one. I had to get a bit of info here and another bit over there and put them together. So I might as well share what little knowledge I've got about the subject.
General Idea Behind Timelapse Photography:
The general idea is take a series of photographs of the same location (without changing your frame) within a consistent interval. For example every 2 seconds you would take another picture. Once you've taken all of your shots you would put them in sequence using a variety of different programs to set the pictures into motion. Keep in mind to make video out of pictures (which is what video is) it takes a ton of pictures. Typically the industry standard is either 24 fps or 30 fps (actually 29.97 if you want to get technical about it).