This can have more than one meaning.
When discussing networksA collection of items like computers, printers, phones, and other electronic items that are connected together by switches and routers. A network allows the connected devices to talk to each other electronically. The internet is an example of an extremely large network. Your home network, if you have one, is an example of a small local network., the core is the heart of the network where much of the trafficRefers to any kind of electronic message -- email, web request, streaming video, or anything else -- that travels over a network. (or at least that part that has to go a long ways to its destination) moves. This is in contrast to the edgeThis term is slightly confusing because, in different contexts, in means slightly different things. In general, when talking about networks, it refers to that part of the network where devices (computers, printers, etc.) are connected. That's in contrast to the core, which is the middle of the network where lots of traffic gets moved around. — the outer part of the network where devices like computers and printers get connected.
When discussing computers, you can think of it as the same as a CPUStands for "central processing unit." Basically, it's a microprocessor - the main one in the computer. Things get a bit more complicated because, these days, there may be more than one microprocessor. But you can safely think of all of them together as the CPU..