At its core, a computer doesn't understand words, images, or sounds. It only understands electricity. Specifically, it understands whether a current is on or off. This simple on-or-off state is the foundation of all classical computing. To work with this, we use a system of two symbols: 1 for "on" and 0 for "off." This is called the binary system.

A single bit isn't very useful on its own. But by stringing bits together, computers can represent incredibly complex information. Each position in the string has a value, and by adding them up, we can create numbers, letters, and everything else you see on your screen. Groups of eight bits are so common they have their own name: a byte.

Representing information is one thing, but processing it is what makes a computer powerful. This happens through millions of tiny electronic switches called transistors, which are arranged into circuits known as logic gates. A logic gate takes one or more bits as input and produces a single bit as output, based on a simple rule.

Let's look at the three most fundamental gates.

The simplest logic gate is the NOT gate. It's an inverter. It takes a single input bit and flips it to the opposite value. If you give it a 0, it outputs a 1. If you give it a 1, it outputs a 0.

The AND gate makes decisions based on two inputs. It only outputs a 1 if its first input and its second input are both 1. Otherwise, the output is 0. Imagine a locked door that requires two keys. You need Key A AND Key B to open it. If you only have one (or none), the door stays locked.

The OR gate also takes two inputs. It outputs a 1 if its first input or its second input (or both) are 1. The only way to get a 0 from an OR gate is to provide two 0s as input. Think of a room with two light switches. Flipping either Switch A OR Switch B will turn on the light.

By combining these simple gates in complex ways, computers can perform any task you can imagine, from basic arithmetic to running a video game. An operation like adding two numbers is just a sequence of these elementary logical steps, performed at incredible speeds. Every action on your computer boils down to these fundamental rules.