The Internet turned 25 years old this year. Sir Timothy Berners-Lee, the British computer scientist who invented the World Wide Web, recently fielded a question on Reddit.com: What was one of the things he never thought the Internet would be used for, but has actually become one of the main reasons people use the Internet? He responded with the one word to explain it all: Kittens. So why would he say that? The following are some top theories.