Adobe’s first open source type family
Paul Hunt, writing for Adobe Type on the factors that influenced his design decisions for Source Sans:
The immediate constraints on the design were to create a set of fonts that would be both legible in short UI labels, as well as being comfortable to read in longer passages of text on screen and in print. In thinking of typeface models that accomplish these tasks well, I was drawn to the forms of the American Type Founders’ gothics designed by Morris Fuller Benton.
Beta testers were an important part, too.