This icon was originally a dog character in the Cairo "hieroglyphic" font that shipped with the original Macintosh. Perhaps because the spots looked a little bovine, it became known as the dogcow. ... A version of this image was used in Mac software for a time to indicate portrait or landscape mode.

An effort to modernize the hourglass wait cursor.

The flip side of the happy Mac was designed to indicate a problem.

A cursor meant to resemble a hand sliding on a piece of paper on a table seemed better than the alternatives, which mostly featured images of paper and arrows. In general, it seems as if there are plenty of arrows in most applications, so it's good to avoid adding any more.

The inspiration for this abstract image appeared in a symbol dictionary, described as something used to denote an "interesting feature" for Swedish campgrounds.

The square shape serves a few purposes: calling attention to itself by using all the pixel real estate and a lot of black, and differentiating the alert from the irregular shapes of most of the other system icons. The border crops the face, so it can represent any person.

An icon in 32 x 32 pixels, created using MacPaint on the original Macintosh computer while the subject posed for his portrait.

Category icon for a wine and food application.

One of the most popular Facebook virtual gifts -- love and happiness!

A virtual gift to symbolize nighttime celebration.