Bit in Computer Science

Introduction – Numerical Systems

Before getting into the subject of computer science let’s talk a bit about what a “Bit” is in different contexts.

The word “bit” comes from “binary digit” which means “binary digit” in Spanish.

The digit, to generalize, is a quantity that is represented by a symbol that has a value in some numerical system.

This may sound complicated, but let’s look at the decimal system we use in everyday life. This system is composed of 10 symbols that we call numbers (0,1,2,3,4,5,6,7,8,9).

Each one of these symbols has a different value from the others, for example if we have two different numbers we can order them from greater to smaller.

It is also said that the decimal system is a “positional” system, that is to say that a digit acquires value according to the position in which it is located. This is something we are taught at a very early age, the subject of “units”, “tens” and “hundreds”.

The values 1, 10 and 100 are composed of the digit 1, but this is in a different position, this changes its value.

A 1 in third position is worth ten times more than a 1 in second position and a hundred times more than a 1 in first position. This is something we have internalized but putting it into words can be difficult to understand.

Then the bit is a digit of the binary numerical system, that is to say a system that instead of having ten different symbols has two, the 0 and the 1.

Boolean Algebra has been developed on the binary system that defines the logical operations between binary numbers.

What is a Bit in Computer Science?

In computer science the “bit” is the basic unit of information, which allows us to discern between two states.

The bits are grouped into binary words. An 8-bit binary word is known as Byte and allows us to represent 256 different states.

Processors in conjunction with RAM and ROM perform operations using binary words.

One way to understand how processors work is by studying the basic architecture of computer, which describes the principle of computer operation. Here is an link with more info.

Then using bytes (which are composed of bits) it is possible to represent increasingly complex information, not only numerical, but also text, sounds, images and perform logical and mathematical operations on that information.

For example, using 3 bytes we can represent any color in the RGB system, one byte for the red channel, one for the green channel and one for the blue channel.

Another example could be that using a byte we can represent a character, then a phrase will occupy a space in the memory proportional to the amount of characters that compose it.

The size of Information

I invite you to do a small experiment to see the space occupied by our information.

We open the notepad and paste the next sentence without the quotation marks:

“The letters that make up this phrase occupy a certain space in memory.”

Figura 1 shows this text but in spanish.

notepad with the phrase: The letters that make up this phrase occupy a certain space in the memory. This is used to explain what a computer bit is.
Fig. 1: The notepad opens and the sentence of the article is pasted.

Then we save the file to the desktop to find it easily.

.txt file made in notepad used to explain what a computer bit is.
Fig. 2: The file is saved to the desktop for easy retrieval.

Finally we open the properties of the file by right clicking on the file and then on properties.

property window of a txt file used to explain what a bit is in computing. Weight of information in memory.
Fig. 3: The properties of the file show that it weighs 80 bytes.

In this case the text that has 80 characters occupies exactly 80 bytes.

This is not always so accurate because in a text file not only characters are stored. In addition, programs can use compression methods to represent the same information in a more compact way.

What is a Bit at the Hardware level?

It is said that computers work with ones and zeros, this is true at an interpretative level, physically the bits are implemented with voltage or voltage levels.

Microprocessors are systems made up of millions of transistors, which are electronic components that behave like three-contact electronic switches. When voltage is applied to one contact, current flows through the other two.

Using transistors, logic gates are implemented, which are grouped into increasingly complex digital systems.

RAM, which is a volatile memory, temporarily stores bits in the form of voltage levels.

On the other hand the Hard Disk stores bits in the form of magnetic fields using the property of magnetic hysteresis that some materials have.


A bit is a binary digit that can be worth 0 or 1, is part of a numerical system analogous to the decimal system we use.

The bit is the basic unit of information used in computing. Grouping bits into binary words can represent all kinds of data such as numbers, text, images, sounds, etc..

The bit is a concept that is applied at the software level to analyze the information and the logical operations that are performed. In microprocessors this translates into voltage levels or magnetization in the case of magnetic hard disks.