Bitcoin is open source. So a lot of people have worked on it.
It begin 5 years ago or so when someone using the pen name of Satoshi Nakamoto published a 9 page whitepaper on the bitcoin protocol on a cryptography mailing list. The start was pretty slow with only a few people interested in it initially. The 9 page white paper is pretty awesome to read too - however it is a bit technical.
http://bitcoin.org/bitcoin.pdf