Hacking is a minigame that must be completed to access locked computer terminals.
The player is presented with 2 columns of characters containing words and various non-alphanumeric characters. Selecting a word that is not the correct password will generate a note of how many characters are correct in that guess. Specifically the number of characters in the guess that match the same positions in the correct password. A player can then compare additional words and eliminate any that do not fit the known data. Exhausting all guesses without finding the correct password will lock out a terminal. The game can be exited and started over, though one must sit through a much longer startup and the password/guesses will not relate to those seen previously.
Among the characters on screen there are often pairs of brackets on the same line - () {} [] <> - that will either reduce the number of words to choose from or reset the number of attempts a player can make. Searching these out first can drastically reduce the pool of words before making a guess, but will likely waste any reset to the number of guesses. Searching them out after using all but one guess will maximize the chances of getting a full set of additional attempts, at the expense of the first guesses being from the largest pool of possibilities. At higher difficulties there is less chance for pairs of brackets to fit on a line but there are also fewer possible words as they are much longer as well - often making higher level terminals easier to guess.
The Computer Whiz perk allows the player one additional attempt to hack a previously locked out terminal