It's, uh...basically, pictures of cats with captions on them that get floated around the Internet. Some of them are actually useful and actually funny, some of them are the kind of things that 50-year-old ladies show their friends, some of them (recently) have dead baby jokes on them. Currently, there's a little online war between the people who like the dead baby jokes and the people who like the cutesy pictures of cats saying cutesy things. My money would be on the dead baby people, but the cutesy cat ladies have them outnumbered.