Since a lot of the users are just getting back into Tennis or looking to learn, I thought I would let you know about a site called Tennis Tips which helps people learn through video and/or explanation. See the description below:
Tennis Tips - Learn about the game of tennis Tennis Tips. This is the home of high-end tennis. If you are a visual learner then this is the site for you. There are video demonstrations as well as images to show and take you step by step through the process of learning the game. If you are not a visual learner then in that case, you can enjoy the text that also takes you step by step to improving your game. This site is designed to teach you the fundamentals and right techniques of tennis.