Community Submission - Author: Henrique Erhardt

In cryptography, the word hash refers to the output produced by a hash function after a piece of data is submitted (mapped) through it. Other than simply hash, the output produced by hash functions may also be referred to as hash value, hash code, or digest. 

To better understand what a hash is, it’s worth discussing what are hash functions and how they work.

Hash functions are mathematical algorithms that convert an input value of any size into an output (hash) of fixed size. In most cases, the output consists of a hexadecimal number. This means the hash is often denoted as a combination of numbers (0 to 9) and letters (a to f).

For instance, if we use the word “Binance” as the input value, and map it through an SHA-256 hash function, the output value (or hash) returned will be:

f1624fcc63b615ac0e95daf9ab78434ec2e8ffe402144dc631b055f711225191

Note that it doesn’t matter how many times we perform this action, the output will always be the same (as long as the input doesn’t change).

On the other hand, any minor change to the input will cause the hash function to return a completely different hash as the output. For example, if we submit the word “binance” instead of “Binance” we would have the following hash as a result:

59bba357145ca539dcd1ac957abc1ec5833319ddcae7f5e8b5da0c36624784b2

Hashes are useful for verifying the validity of certain information, without revealing what the information is. In practice, hash functions may be applied to various scenarios. A few use cases include database lookups, large files analyses, and data management.

When combined with cryptographic techniques, we have the so-called cryptographic hash functions. These are extensively used in information-security and are an essential part of most blockchain networks.

For instance, the Bitcoin blockchain has many operations that involve hashing, and these are crucial in the process of mining.