Time lapse is a series of photos, depending on what your time lapsing how many photos are took, or a recording sped up to create a fast speed video.
This is an example of a time lapse taken from space by NASA of Hurricane Sandy.
http://www.bbc.co.uk/news/world-us-canada-20129277
I think this is a very good example of a time lapse and shows things through a period of time. The way the photos have been taken you cannot tell that it was a time lapse.
another example is of this video from YouTube showing someone growing facial hair over a long period of time:
I think this works well because i like the way the pictures are very short and snippy which make the time lapse look very interesting.
To create a time lapse you set a camera up in a certain place you want to record. You then have to set the camera up to take a picture every few hours or even days to see what has changed, next you then go back to the camera after a certain period of time to see what the photos are like. You then use all the photos to create a video animation.