According to the official definition of a computer by Oxford Languages, a computer is "an electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program."
The smartphone and tablet you carry around with you is actually considered a computer! The oldest computer is probably the Antikythera Mechanism, an ancient Greek computer developed in the 2nd Century BC. This was an analogue computer used to calculate astronomical positions and eclipses.
Modern day computers are typically comprised of a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), Memory (RAM), and some kind of storage device like a Hard Drive (HDD) or a Solid State Drive (SSD). You may hear the words "computer specifications" or "computer specs" thrown around. Your specifications (often abbreviated as "specs") is really just the hardware that makes up your computer. Examples include your graphics card, your processor, memory, etc. Computers also include miscellaneous hardware that holds the computer together, such as your motherboard and the computer cooling.
Higher quality specs often mean more powerful and more expensive hardware. As more powerful hardware is capable of running more intensive software and games, these types of computers are highly prized. For more detailed information and comparison on computer specifications, you can try visiting the channel Linux Tech Tips.