The movies were based on the books. Michael Crichton wrote them. They're both great. The overall story for the first movie and book line up, with a moderate amount of plot differences, and almost entirely different details. The second movie barely has any similarities to the book. Aside from it being on a second island, the main characters are named Ian Malcolm and Sarah Harding, and a trailer gets pushed off a cliff by two T-Rex's, it is totally different.