In 1974, Dennis Ritchie and Ken Thomson published the first paper on Unix. 

After the paper, research labs and universities wanted to try out Unix. 

At&T was forbidden from entering the computer business, under a 1958 consent decree in settlement of an antitrust case. 

Hence, Unix could not be turned into a product. 

Bell Labs was required to license its non-telephone technology to anyone who asked. 

Ken Thompson quietly began answering requests by shipping out tapes and disk packs - with a not signed "love, ken".

Thus began UNIX. 

From: The Art of Unix Programming