What is a code?

Ekaterina Ermolaeva
Ekaterina Ermolaeva
October 20, 2014
What is a code?

In the modern world, we very often meet with codes when performing various operations. What is the code?

The code is called a certain combination of characters, which is auxiliary for understanding a message or for performing an action.

Codes may consist of numbers, letters, signs, sounds. What does each code mean? Consider the most popular types of codes.

Code as an algorithm

It consists in a certain sequence of actions for the commission or confirmation of any operation.

Genetic code

This is a specific sequence of nucleotides in the DNA and RNA chains in living organisms. With its help the hereditary information of each individual is recorded.


It stands for "personal identification number" - an analogue of a digital signature. Used to access cash cards - credit or SIM cards. Read more about this in the article What is the code of the card.


This information in the form of strokes applied to the packaging of goodsin order that it could be read out by special devices at sale.

QR code

In short, this is an improved version of the barcode. Only created in a matrix, in two-dimensional space. You can read more about this type of encoding in the article What is a QR code.

CVV code and CVC code

This is a code consisting of three digits and indicated on the back of a credit card. It is used to confirm payments when paying by card without contacting the payment terminal, for example, via the Internet.

Machine code

The system of commands for a certain type of computer that ensures its operation.

Byte code

One of the simplest types of machine code that performs simple operations.

Shell code

Computer code that transfers computer control from the user to the shell. Often used by hackers.

Code as a cipher

Allows you to encode an informational message using a specific character set. Here, each character has its own encoding. A striking example is Morse code, where each letter corresponds to a specific signal.

The method of encoding information is selected in each case individually, depending on its purpose.