With the invention of the printing press, came a new industry, Publishing. The good news for authors was that their works could be reproduced in large quantities. The bad news was that authors and writers now needed protection from these same publishers in order to receive fair compensation for each reproduction of their work sold. In order to insure the author would receive this compensation, more than a handshake was needed. The first contracts were a simple agreement between the publisher and author.
Publisher agrees to pay author a percentage of each book sold.
For awhile things were going along quite well and everybody was happy. Then, one day, the owner of a local theater read a novel and decided it would make an interesting play. In the early days of horse and buggy when books were delivered only to a small area, local rights were all one needed. The relationship between all parties was going along quite well for most of the 20th century. As recently as 1995, the Writers Market didn't even show a listing for ebook rights.