I'm surprised no one seems to have mentioned this earlier. Everyone's arguing about what image the icon contains and thinking of imaginary folks who are using computers for the first time after coming off a ship from a lonely desert island.

Back in 'teh day' when my icons were all cutesy skeuomorphs, my computer came with maybe a dozen apps and most of them were on my desktop. Now, I have over a hundred sitting in my global Apps folder alone - never mind user Apps, sub folders, etc.

This gets compounded even more on phones - on my iPhone, I've accidentally placed 1Password next to the Settings app - both have a grey background with a circular center. Settings' center is grey gears, 1Passwords is a blue ring with a keyhole. On examination, they're not similar at all, but I can't even begin to tell you how many times I clicked on when, meaning to click the other - even _knowing_ the differences and kicking myself each time.

I think a lot of what the designers are trying to do is create an icon that stands out visually, and is easily found from amongst a large set of other icons, rather than trying to impress upon us what its functionality is from a metaphor.