In the late 1980s and early 1990s, prior to the widespread adoption of the Internet, it was common for software developers to upload demos and shareware to Bulletin Board Systems. In most cases, demos or shareware releases would contain an advertisement for the full game with ordering instructions for a physical copy of the full game or software. Some developers instead used a licensing system where 'full versions' could be unlocked from the downloaded software with the purchase of a key, thereby making this method the first true digital distribution method for PC Software.