Roboto

Roboto is a neo-grotesque sans-serif typeface family developed by Google as the system font for its mobile operating system Android.

Google describes the font as "modern, yet approachable" and "emotional". The entire font family has been licensed under the Apache license and was officially made available for free download on January 12, 2012, on the newly launched Android Design website. The family includes Thin, Light, Regular, Medium, Bold and Black weights with matching oblique styles. It also includes condensed styles in Light, Regular and Bold, also with matching oblique designs.