Encryption is the process of encoding information in a way that only authorised entities can access it in a decipherable way.
The method of encrypting the information typically uses a publicly available algorithm, but relies on a key which is kept private to encrypt the information.
To decrypt the information back to a decipherable format, the private key will be required.
This means that even if someone were to gain access to the encrypted information they will not be able to understand it without access and use of the private key.
Although, the above concept of encryption and decryption applies to many facets of computing, here we will cover data encryption at rest on storage systems.