G'day all
Well I'm moving on from console and wanting to start to get into PC gaming.(Don't hate me cause I used to play console ). I just don't really understand the specs of a gaming computer, I understand the CPU socket size in a motherboard and the codes for them to go together, the case sizes(ATX, Micro ATX etc). But with all the other parts, like the Graphics Card, HDD, What GB for the HDD, Sound Cards. Well mostly everything apart from the stuff I mentioned before. Also do these parts have to somehow match up with each other or is it all random(Apart from the motherboard and CPU).

Thanks guys much appreciated