Cryptography

Based on maths(complex) and makes internet secure.
Without cryptography there would be no secrets or privacy in digital world.
It takes bytes of data then it scrambled them up with an algorithm making it nearly impossible for a computer to understand it's true meaning without the proper credentials.
Cryptography is science of creating secrets.
Even the strongest encryption algorithm in the world is weak if the user input is weak.
Cryptography is always evolving, starting from 1900 BC(if i'm right).