# Learn How to Become a Hacker: Part 3

### Understanding Binary and Digital Signal

In the previous lesson we discussed binary code as a representation of “on” and “off” or 1s and 0s. We further described this concept as a type of electronic pulse. In this lesson, we are going to build on our understanding of binary to develop a more accurate definition and conceptual understanding of binary code. Finally, we are going to learn how binary code relates to digital signals.

Binary actually predated computers. Binary is just a system of counting. Binary, mathematically, is a base-2 numeral system. This will be important when we discuss how to understand IP address, subnet masking, and different types of computer architectures. We will cover binary mathematics and how it relates to computers in the next lesson.

In electronics, electricity can only be efficiently represented in binary. Electricity flowing in a circuit can only be one of two states, on or off. So it makes sense that we use binary code to represent information in a computer. What is actually occurring within a circuit is either a presence or excess of electricity or a deficiency or lack of electricity. This is also described in simple terms as on and off. To represent this in a way that humans can understand, we use 1s and 0s (binary). The best way to understand binary code and how it forms the basis for information transmission, is through the computer’s central processing unit (CPU).

Within a computer’s CPU, there is a component called the arithmetic logic unit (ALU). The ALU is comprised of logic gates that handle all mathematical and logical operations within the computer. As we discussed, the computer is made up of electrical circuits. These electrical circuits can only represent two states, on and off. We represent these states as 1s and 0s (binary). Although this may seem very limited, these two states mathematically provides the computer with everything it needs to do the most complex things known to man.

The ALU processes binary code through a series of very small circuits called logic gates. The most common logic gates are NOT, AND, OR, XOR, NAND, NOR, and XNOR. These logic gates are made up of one or more transistors or semi-conductors that will turn circuits on or off. Each transistor within a logic gate can be turned on and off. When these transistors are switched on and off in a proper sequence, the logic gate is manipulated to also turn on and off. Within the ALU there are millions of gates that contain billions of transistors. These millions of gates are turning on and off representing binary code at the speed of light. With this complex system of on and off, we can represent numbers through binary mathematics which controls the computer and all of its hardware components. When binary code is processed in the CPU and transmitted to the other hardware components, a digital signal is created. These digital signals are just electrical pulses and electrical waves that are organized through binary mathematics within the CPU. Through binary mathematics and digital signal, communication within and through computers is possible.

In the next lesson, we are going to cover binary mathematics and how this becomes information that we can see and understand on our computers screens.