Idea of PHP Icon
It's a black unfilled square with slightly rounded corners. The radii of the rounded corners is very small. In the center of the square there are the letters "PHP" in upper case.
This PHP icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,200 icons, all in the same style and quality.