Computers get things done as a result of a combination of hardware, software, input, and output. The CPU, or central processing unit, is where most of the heavy lifting occurs. While the technical aspects of what makes computers work could be difficult for a non-professional to understand, the mechanical aspects of it can give you a clear idea of what and how things happen inside.

Computers work thanks to a series of hardware devices that are closely interconnected. When looking at a computer from the outside, the basic parts are the system case, which may be a tower for a desktop machine or the body of a laptop; the monitor; and the keyboard. A mouse or trackpad may or may not be essential to the functioning of a computer, depending on the type and model. Many computers also have a CD or other disc drive in the case.

Most of the essential things that make computers work are inside the case, away from your eyes. The motherboard is central point of the computer, where all the various components attach and communicate with each other. Key to allowing a computer to work is the central processing unit (CPU), the central stop for all the processes the computer goes through. As a command is sent, such as "open a program" or "turn the monitor on," the CPU interprets this order and then acts accordingly.

Once the computer is turned on, or booted up, the CPU goes on to activate certain sections so that it can then give you access to programs and processes. Computers work based on the CPU granting access to users, so if the booting up process malfunctions, it can mean that the computer cannot be used, even if everything else inside is working properly.

Memory is also extremely important to allow a computer to work. The two main kinds of memory are Random Access Memory (RAM) and Read-Only Memory (ROM). ROM is stored data, and cannot be written to; RAM is memory that can be read from and written to, allowing new data to be saved. In many cases, additional RAM can be added.

One kind of ROM is the Basic Input/Output System (BIOS), which is in charge of communications between the software on a computer and the hardware. When a computer is first turned on, the BIOS checks basic data such as hard memory, RAM, any cards installed, and other devices. BIOS also checks for booting up errors and offers to fix them if necessary.

Other less central — but no less vital — parts that let computers work include the power supply, transformer, and battery. These parts make sure each component gets the electricity it needs in the proper amount, and that key information is saved even when the power is off. The computer drives, including hard drives, flash drives, and any drives with removable media, such as CD-ROM drives, allow the user to upload new data and applications to the computer and save files. The cooling system helps keep all of the components from overheating.

Most computers also have other components without which a computer would be more difficult to use. Graphics cards allow the computer to display graphics on the monitor, and come in many different levels. Sounds cards allow the computer to play sounds. Connecting to the Internet or other computers requires a modem. Most computers come with all of these components, and often it is possible for the owner to upgrade each to newer or more advanced versions.

Input/output (I/O) is the name given to the processes or components needed to interact with the CPU and make computers work. These include the monitor and keyboard, but also CD-ROMs and removable flash memory cards. Input/output processes allow you to order the computer to do something, making the essential for interaction and use.