# Hash Functions

Learn hash functions with a specific focus on the keccak256 algorithm.

## We'll cover the following

Our journey starts with cryptography. It starts here because cryptography is a critical component of blockchain technology—it is used to secure the data stored on the blockchain. Without cryptography, the data in the blockchain would be vulnerable to attack.

Before understanding how encryption and digital signatures work, we need to understand hash functions. They are a fundamental part of modern cryptography used in almost all cryptographic systems. As the famous cryptographer

## Functions

In computing, a **function** is a process or relation that produces a specific output for a given input. Functions are written in a programming language because this is how machines understand them. A computer can apply the set of rules that describe how the output is produced from the input to those functions.

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