I've saved the most difficult post for last in this run of summer-holiday-posts. The user. There are so many ways to represent a user, so the way you draw him/her depends on your context, on what you want to achieve. Note: All the "meanings" or "moods" written under the figures are my own. You can perceive them in a different way. The perceived meaning of symbols are heavily influenced by environment and culture.
Servers are generally depicted as either a square computer hard disc as we know them from stationary computers, or large, square boxes with smaller square discs inserted (Which also looks a lot like a stationary computer). I wish there was some cool story behind their look, but there isn't. That's just how they look.
There are two well established icons or symbols that are used when we're talking wireless networks. There is a difference between the two. One is the transmitter of a wireless network, the other is a hot-spot of a wireless network.
I've only recently gotten to know databases. How they work, SQL and the different scripts you can use. I love it. I think it's so much fun going into different databases when testing, viewing, comparing, joining and editing them. Even though the amount of trouble you can cause in there is immense.