One of the earliest encryption methods, Ciphers, were used to encrypt plaintext into something called ciphertext. The simplest way to do this would be to use a Caesar Cipher. Named after Julius Caesar, Caesar encrypted his messages with this cipher, making messages seem like gibberish to the normal eye, but very easy to decrypt. Anyways, enough with the caesar cipher history lesson, let's move on to other ciphers.
A Vigenère cipher uses what a Caesar Cipher built a basis on, except an alphanumerical key is used.\
Caesar cipher only has 26 usable values,
This makes the Vigenère cipher a lot harder to crack. These further advancements lead to much stronger encryption, making messages harder to crack, due to an increase in the number of charcters used to encode / encrypt the messages.
This Vigenere cipher was also used in this writeup from DawgCTF 2020.