It's a logo for the Apple iOS operating system. The middle of the logo are the letters "i" "O" and "S" where the "i" is lowercase and the "O" and "S" are both uppercase. The letters are placed inside of a square with rounded edges.
Related to iOS Logo Icon
Related icons are the icons with matching tags, as well as all logos icons. All icons are in the same flat style. You can either download free PNG icons or buy SVG vectors