Open Sans is a humanist sans serif font designed by Steve Matteson and published by Ascender Fonts. By far, Open Sans is the most popular font out there at this moment. Containing an 897 glyphs chars set, Open Sans’ friendly appearance was optimized for print, web, and mobile interfaces, and has excellent legibility characteristics in its letter-forms. We also use it as a webfont here on Kreativ Font 😉 … a must have for everyone!
Open Sans webfont is also available for free use from Gooogle Fonts