A password is a string of characters used for authenticating a user on a computer system. For example, you may have an account on your computer that requires you to log in. In order to successfully access your account, you must provide a valid username and password. This combination is often referred to as a login. While usernames are generally public information, passwords are private to each user.
Most passwords are comprised of several characters, which can typically include letters, numbers, and most symbols, but not spaces. While it is good to choose a password that is easy to remember, you should not make it so simple that others can guess it. The most secure passwords use a combination of letters and numbers and don not contain actual words.