1. Introduction to Hashing

Hashing is a technique that allows you to 'map' data of variable length into a fixed-length data value (which is effectively just a large number).

This number remains the same length, no matter how long the original string was. The number is quite long, so it is usually shown in hexadecimal. For example, here is what this entire paragraph looks like, once converted into a 128-bit hash using the MD5 algorithm:

                          71e8841e0cda4bafac105dfada09d9b2

Hashing algorithms use complicated mathematics to convert strings into hashes. You won't need to know the details of how hashing algorithms work, but you will need to know what hashing is useful for.

We have a separate section describing hashing for database indexing HERE

This section will discuss other uses of hashing.