Cryptography introduction and cheatsheet

Cryptography, an interesting word most people do not understand. It is nothing more than the art of sending messages which are protected from spies, you convert them into a secret code with the use of an algorithm called "cypher". It has altered the course of history because it has been decisive during war times. There are many cyphers out there, some of which have been used for centuries, some which are still being used today, specially when you use the internet, after all it is necessary to make sure you can access your bank account, send Whatsapp messages and shop online with security, we can't allow some hacker to tap into your internet transmission and steal all your data, therefore everything must be encrypted before it leaves your computer, and it must be decrypted as soon as it arrives at its destination, which could be someone else's computer or some data center. Although it seems complex, the principles are actually simple, all you need to do is to f