How to encrypt and decrypt a file

In Linux there is a utility 'gpg' which is used for encrypting and decrypting of  files.
Syntax -

$ gpg -c filename

[ It will then prompt to enter a pass phrase and it will create a file 'filename.gpg' ] 

Enter passphrase:<YOUR-PASSWORD>
Repeat passphrase:<YOUR-PASSWORD>

To decrypt -
 $ gpg filename.gpg        

[ Now give the same pass phrase to decrypt the file ]

gpg filenme.gpg
gpg: CAST5 encrypted data
Enter passphrase:<YOUR-PASSWORD>