Open Sans is a humanist sans-seriftypeface designed by Steve Matteson and commissioned by Google. It was developed with an "upright stress, open forms and a neutral, yet friendly appearance," and is optimized for legibility across print, web, and mobile interfaces. Its design is almost identical to that of Droid Sans, with the exception of wider characters and the inclusion of italic variants. Whereas Droid Sans is used primarily in the user interfaces of some Android phones, Open Sans is used in some of Google's web pages as well as its print and web advertisements.
Open Sans is available in a large number of variants for a font with an open license. There are 5 variants for weight (300 Light, 400 Normal, Semi-Bold 600, Bold 700 and Extra Bold 800) and each one has an italic version, totaling 10 variants. There's also a separate font called Open Sans Condensed with 3 width variations.