Too Long; Didn't Read
There are two types of encryption - Symmetric Key encryption and Asymmetric Key Encryption. The difference between encryption and encryption is that encryption needs a key to encrypt/decrypt. Only someone with a key can view the unencrypted data, and only the user can read it. Developers should only ever use encryption algorithms and libraries that have been thoroughly tested. It's hard to create an algorithm that no one else can break, even after years of analysis by the best cryptographers around.