Symmetric key in cryptography

Question

In symmetric key cryptography the same key is used to encrypt and decrypt the message. What is that key?

Answer 1

Yes, the same key is used to encrypt and decrypt the message. A key is a piece of information (a parameter) that determines the functional output of a cryptographic algorithm. For encryption algorithms, a key specifies the transformation of plaintext into ciphertext
and vice versa for decryption algorithms.