SHA3 (Secure Hash Algorithm 3) is a cryptographically hash function that translates any input into 160 bits. It is important to notice that any arbitrary data (be is a 4 bytes string, an image or a 10GB movie) will be hashed into 160 bits. SHA3 is deterministic, this is, always output same result given same input. It is important to notice that from a while ago, SHA3 is no longer considered secure against criptographic attacks.

SHA3 is based on the principles similar to those of MD2, MD4 and MD5 but it generates a larger hash value.

SHA3 algorithm will hash inputs into 160 bits. Usually the most common way choosen to represent those 160 bits is using hexadecimal notation, that is, grouping the bits in groups of 4 bits, which ends up being a string of 40 characters.

As an example, SHA3("world") = 169d8c1d9447d349170d643a2f5a4df8ecfd615568fb50cc218a346c3b934538a8f566d906ae55c63bcf85130b833b4c4bb9758035b88a78820a5c446ed8636b

In 2006, NIST (National Institute of Standards and Technology) organized a competition to create a new hash standard. Because of the previous successful attacks in MD5, SHA0 and SHA1, NIST perceived the need to create a different standard (important to mention that no significant attack on SHA2 has been done yet)