The basic Facebook logo that acts as the icon for the app on a smart phone is a blue square with soft edges and a thick, white, lower-case f inside. The f is off-centered to the right with some space on top and on the right, but the bottom of the f is flush with the bottom of the square. As for the shape of the f, the main vertical part of the f has a wide curve at the top and ends at horizontally with a 90-degree angle. The horizontal part that crosses to make the f is a rectangle of sorts. The left side of the rectangle has perfect 90-degree angles, but the right side end cuts down to the left diagonally. Therefore, the right ends of the top part and middle part of the f aren’t completely flush with each other.
The other logo used for Facebook is a blue rectangle with the whole word in the same white letters. All the letters are lower-case and the same font or style as the f in the app logo – chunky, curved, fairly close together, and somewhat playful. The top parts of the b and k cut down diagonally from right to left just like the right side of the f does.