Symmetric vs Asymmetric

To master cryptography you first need to know the basics like how it works? First you have a plaintext that you want to encrypt using what's called an encryption key or cipher. Now its encrypted with a key so you may need the same key to decrypt it back into plaintext but there's usually another key for that if your talking asymmetric encryption but for now we'll use symmetric since that's usually how your house key works.

One key however can open more locks but I wouldn't recommend that if your talking about securing your own data? Asymmetric is two keys like how a simple substitution cipher works.