Brute Force Attack (also known as brute force cracking) is a trial and error method used by application programs to decode encrypted data such as passwords. In a brute force attack, automated software is used to generate a large number of consecutive guesses as to the correct value of the target.
Some forms of brute attack might try every word in the dictionary to see if it can get a correct hit whereas other types of attack might try commonly used passwords and combinations. Attacks such as these can be time-consuming and success is usually determined by sheer computing power and the number of combinations tried, hence the name, brute force.
Thankfully there are some easy steps you can take to minimise the success a brute force attack may have on your computer systems. These include requiring users to create complex passwords and also limiting the number of times a user can unsuccessfully attempt to log in. Temporarily locking out users after unsuccessful login attempts is also a good way to hinder brute force attacks.