Symmetric Encryption
In plain terms
Encryption using the same key to encrypt and decrypt.
Going deeper
Symmetric encryption uses one shared secret key for both operations, making it fast for bulk data but requiring secure key sharing. Both parties need the same key.
Under the hood
Efficient for large data; key distribution is the challenge, often solved via asymmetric exchange.
Examples
AES, disk encryption, TLS session encryption, file encryption.
Think of it like...
Like a single key that both locks and unlocks the same box, you must share it safely.