The basics of a computer are just two things;
- a "processor" (CPU for central processor unit), with some memory
- and some input/output (a fancy of way of saying that the CPU needs to talk and listen to other things)
A computers "memory" is similar in concept to your own - it is where it/you put things and later look them up (remember them). However, computers are much better at that than we are.
There are two basic types of memory:
With people, short term memory is electrical, and the stuff you repeat or you'll forget (like a phone number when you first hear it), because if you get distracted the "power" will be switched somewhere else, and you'll forget it. Computers have similar memory called "RAM" (Random Access Memory), which allows the computer to remember anything, while the power is on. If you turn off the computer, everything in RAM is gone.
So computers and people need "long term" memory. For people this is a chemical process in the brain so things are "etched in" and last longer. For computers, this information is usually stored on a disk drive or Compact Disc for later retrieval - and that's where you save things you want to keep while the power is off (or the computer is doing other things).
Now the I/O (as Input/Output is referred to) needs to interface (talk/listen) to other things. There are a few basic things the computer interfaces with; it's own memory, and I/O cards or ports that are connected to other things.
Now the other aspects of I/O are these ports (think of phone jacks where you plug into), which talk to physical devices that interface with humans. The keyboard, mouse, monitor, printers, scanners, telephone lines, and so on, all talk through these cable to the "ports" - and ultimately this is how the computer interfaces with everything else. Some ports are built in, and many others are on separate cards so that they can be easily added or replaced as needs warrant.
Each of these ports or card types have special names, numbers or acronyms -- and that jargon is what confuse many people or make it sounds more complex than it is. But the geeky sounding names like USB, PCI, VGA, WiFi / 802.11, Ethernet, blah, blah, blah, are just different names for what can plug in where. Each has a special function or something that it does - but though they sound worse, this isn't much different from you remembering that a wall electrical socket is different from a faucet, phone jack, cable hookup or air-vent. They each have a different name and function, and you won't get the expected results if you get them confused.
How does it work?
So how does a computer work? Well basically it helps to think of the oldest computers: either music boxes, player piano's, or mechanical "programmable" looms. You put in "programs" like old drums, wheels or paper rolls in music boxes, and the computer just takes each row of dots/nibs and does something with it. Instead of playing a note, the CPU executes a simple instruction like moving one location of memory, testing one small thing, or adding/subtracting one thing from another. If you put a lot of those simple instructions together you can make simple routines, like test which key was pressed or what menu was selected and so on. If you put hundreds of these routines together, you make small programs (or applications).
Dozens or hundreds of small applications work together to do all the things that computers do. But still at their heart, they're just sophisticate player piano's - you put in the roll of paper (or the program), and the computer plays it and gives you the results you asked for.
So computers really aren't hard to understand, now are they?