DogeOS opened the public testnet for its Dogecoin application layer on Wednesday, per its press release. A testnet is a trial version of a network, where developers test apps before real money is involved. Jackson Palmer and Billy Markus created Dogecoin in 2013 as a joke. It works as a peer-to-peer digital currency. Since then it has evolved quite a lot, becoming a multi-billion dollar network, a social symbol, and a serious investment for some people with deep pockets.