Symmetric vs asymmetric encryption, key exchange

Encryption turns readable plaintext into unreadable ciphertext using an algorithm and a key, so only someone with the right key can turn it back. It protects confidentiality for data at rest (on disks and in databases) and in transit (across networks). Security+ expects you to know the two families of encryption, what each is good at, and how real systems combine them. Nearly every secure protocol you will meet, from HTTPS to VPNs to encrypted messaging, is a combination of the ideas in this lesson.