Open Source Licensing: What Every Technologist Should Know


If you’re a software developer today, you know how to use open source software, but do you know how and why open source licensing started? A little background will help you understand how and why the licenses work the way they do.

Origins of open source licensing

Technologists today, having grown up in the age of Microsoft Windows and proprietary software, may believe that open source licensing is a recent trend that began in the 1990s. Although open source licensing’s popularity has skyrocketed in the past two decades, in truth, open source was the original model for software licensing, with proprietary licensing coming later.

In fact, the two models for software licensing (open source and proprietary) trace their origins from a common source: the Unix operating system. Unix was developed by AT&T Bell Laboratories in the late 1960s and early 1970s and was the first general-purpose operating system. At that time, AT&T’s market position was so dominant that the US Justice Department issued a consent decree barring AT&T from engaging in commercial activities outside the field of its telephone service, which was AT&T’s primary business. Because of the consent decree, AT&T could not exploit Unix as a commercial product, so Bell Labs gave Unix away in source code form under terms that allowed its modification and redistribution. This led to Unix’s widespread use and popularity among computer scientists in the 1970s and 1980s.

After the US Justice Department lifted the consent decree in 1983, AT&T pivoted to commercialize Unix as a proprietary product and adopted more restrictive licensing terms that allowed Unix to be redistributed only in object code format.