What is encryption and why are there different levels?

Encryption is a mathematical process of coding and decoding information. The number of bits (40-bit, 56-bit, 128-bit, 256-bit) tells you the size of the key. Like a longer password, a larger key has more possible combinations.

When an encrypted session is established, the encryption level is determined by the capability of the web browser, SSL certificate, web server, and client computer operating system.