# Hash Functions

Learn the core properties of cryptographic hash functions and how they're used to compute digital fingerprints.

In this lesson, we'll start learning how Ethereum works. But instead of jumping right into the technicalities of blockchain, we'll start with a foundational topic for understanding blockchains: cryptographic hash functions. While this might seem very theoretical at the moment, hash functions are used so often in Ethereum and other cryptocurrencies that it's worth spending some time to get a good grasp of this topic before we move forward.

## Hash functions

A cryptographic **hash function** is a special algorithm that takes a binary of any size as an input, but always produces an output of a fixed size (e.g., a 32- or 64-byte number depending on the function used). The result of a cryptographic hash function is called a **hash value** or just a **hash**.

Get hands-on with 1200+ tech skills courses.