Bitcoin
Bitcoin is an open source digital currency that utilizes a peer-to-peer payment network to allow digital transactions to take place in a more secure and private way than traditional currencies backed by governmental entities, originally introduced in 2009. Bitcoin is often called a cryptocurrency because of its reliance on public-key cryptography as the primary security measure with buyers and sellers sending payments by broadcasting a digitally signed message that effectively transfers ownership of Bitcoins without the use of any central controlling authority providing regulatory oversight.