Open Sans is an open-source, humanist sans-serif typeface designed by Steve Matteson and released in 2011. The five weights with matching italics make Open Sans extremely versatile and useful for a wide range of applications. It is a ubiquitous font on the web, used by everyone from Google to WordPress. I’ve even heard it referred to as the “flat design” font. I like to think of Open Sans as the new Arial.
Font research done for you.