The base of operations for the brains of a computer is the motherboard. The motherboard serves as a literal foundation for many of the other elements inside your computer. It's a large printed circuit board. The motherboard provides the connections and sockets that let other components communicate with each other. Motherboards come in different shapes and sizes -- a motherboard in a laptop computer might not look like one from a desktop PC.
The computer brain is a microprocessor called the central processing unit (CPU). The CPU is a chip containing millions of tiny transistors. It's the CPU's job to perform the calculations necessary to make the computer work -- the transistors in the CPU manipulate the data. You can think of a CPU as the decision maker.
Another critical component in computers is memory. The two most important kinds of memory are read-only memory (ROM) and random access memory (RAM). Computers can read data stored in ROM, but can't write new data to it. With RAM, computers can read from and write to that memory. Without computer memory, every calculation on a computer would be stateless. That means there'd be no way to preserve information from one moment to the next and every process would start on a clean slate. That's not useful if you want to create complex programs.
Many desktop PCs have the capacity for additional RAM. The user simply has to open the computer and plug RAM chips into the appropriate sockets on the motherboard. But other computers are sealed systems -- you aren't meant to open them and make changes so you're pretty much stuck with what you've got.
A chip called the Basic Input/Output System (BIOS) works closely with the CPU. BIOS is a specific kind of ROM. If you think of the CPU as the brain of the computer, then you might consider BIOS to be the spine. It's the job of BIOS to handle interactions between the software running on a computer and the machine's hardware components.
The motherboard, CPU, ROM, RAM and BIOS handle most of the heavy lifting for computer processes. They're in charge of allocating resources to applications so that they run smoothly. They also accept input from devices like keyboards, mice and other computer accessories.
There are plenty of other components inside your computer. Let's get into the guts of a computer in the next section.