What really is a computer, using technical terms of course, and what is a byte/bit?

Assuming that you mean a modern digital computer, a computer often has different definitions in the computer field on what makes a computer. Based on facts and my opinion, a computer is a something that can be programmed, give output and receive input, has a function, and to an extent, has mechanical hardware. In other words, its something that has both hardware and a sort of software. A bit and a byte are different. A bit is the basic unit of memory in computers. A byte consist of 8 bits or more known as an octet. The term octet is often used in IP addresses but that is another long matter. So in other words, anything with memory capability such as RAM, SDD, Hard drive, Flash drive (USB), and CD/DvDs, all have bits/bytes in them.