A brute force attack that uses common words as possible passwords or decryption keys and may provide a more efficient way of discovering the user's code. Sophisticated dictionary attacks sort words by frequency of use and start with the most likely possibilities; for example, names of people, sports teams, pets and cars. For greater security, users should not use passwords that could be found in an ordinary dictionary. While a dictionary attack can be done by a person manually, it is mostly done via software and a database that contains millions of words. See brute force attack and Captcha.