Decryption is generally the reverse process of encryption. It is the process of decoding the data which has been encrypted into a secret format. An authorized user can only decrypt data because decryption requires a secret key or password.
To make the data confidential, data(plain text) is encrypted using a particular algorithm and a secret key. After encryption process, plain text gets converted into cipher text. To decrypt the cipher text, similar algorithm is used and at the end the original data is obtained again.