system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What actions computer hardware perform

For example Whats the difference between your ram and your processing power, what does a motherboard do, isnt a graphics card similar to ram?
gpt
Ok, let's pretend that a computer is pretty much the same as an office. In this office is a man who has to do lots of work and has an 'In' tray where he gets his orders and an 'Out' tray where he puts the fruits of his labours. We'll call this man the processor (or CPU) and his job is to make sense of all the stuff that's piling up in his intray, but more on him later.

Now, in order to see how this man works, it's important to know how all the stuff gets to his intray. The easiest way to look at this is to imagine a huge warehouse full of papers that he may have to work on. This is the hard drive and it contains all the information the company needs to perform the tasks required of it. The problem is that there's so much stuff in there that it takes ages to find and the warehouse is a long way from his office. So, if he said "I need Document X right now!", some little guy would run to the warehouse, search for it and then bring it back, all of which would take ages. Instead, the company had another room (called RAM) built next to his office for holding documents he knows he's going need that day and instead of the little man having to run all the way to the warehouse for each individual document, he instead gets another chap to pick up a whole batch that he knows he'll need that day and dump them in the room next door. This means it's much quicker to get those vital docs but the down side is that there's not so much space (so only so many things can be stored there) and it also has to be cleared out every time the company shuts for the day (like when a computer gets turned off).

On top of this, there's even faster (yet smaller capacity) memory in the office itself (it's called 'Cache Memory') and this can be thought of as the man's desk. It's pretty small so only the things he really needs can sit on it, but it's very quick for him to access.

Still with me? Good. Ok, the other thing about this man called 'Processor' is that he's only really good at certain, general purpose jobs and there are other things that other offices in the building are better at. For example, graphics are really hard work so he subcontracts that to an office called the 'Graphic Card'. This is just down the corridor and works in the same way that his does (so stuff comes from the warehouse to RAM), but he has an additional room next to him that's sole purpose is to store the graphics information so he can get to it really quick. You can think of this as video memory. Some companies like doing the graphics work so they put a really brainy guy in there and make his Video Memory room massive. In computer terms, this would represent a high end graphics card. Others don't care so much so they put an intern in there and insteady of giving him his own dedicated memory room he is simply allowed a few shelves in the main RAM room. This is what Intergrated Graphics look like. 

The same goes for sounds. Now, modern processors are pretty good at dealing with sound but they weren't always so again, the man used to subcontract work to a special Sound Card and that worked in pretty much the same way as the graphics department.

Now, as is becoming clear, all these different rooms need to exist within a building and that's where the motherboard comes in: It's essentially houses all these different places and joins them up with a system of corridors. Some of these corridors are very wide and busy (like the one between the warehouse and the RAM) while others are less so (like from the keyboard to the processor) but they must all link up so that the little man in the office can get access to the other rooms fairly quickly.

And that's the simple version.