Question: What is AJAX ? 

Answer: Ignore the 2Point Hounds. They didnt even bother to look at the category of this question. The first answer is technically correct. An example would be nice.  How about Netflix where you can rate a movie.  Clicking one of the stars updates the database behind the scene with your vote but the page does not refresh.
This question from the Yahoo Q&A forum is categorized in the topic: Society & Culture