Calibri
LucasFonts · Luc(as) de Groot · 2007

The rounded humanist sans that replaced Times New Roman as Microsoft Office's default, likely the most-seen typeface Luc(as) de Groot has ever drawn.
About
Calibri was built for Microsoft's ClearType Font Collection, with softly rounded terminals designed to read well on screen at small sizes. It became the default in Word, Excel and PowerPoint in 2007 and has stayed there for most users since, making it one of the most-printed typefaces in the world by sheer volume.
Classification
A rounded humanist sans commissioned by Microsoft as the ClearType-era default UI and document typeface, replacing Times New Roman as Office's standard.