A Quick-time Event (also known as QTE) is an event during gameplay where the player must act in a certain manner to survive, or for the remainder of the game to take place in a certain way. The first instance of a QTE was Resident Evil 3: Nemesis, where the player would be forced to decide on two outcomes within a time limit, which may effect the progression of the story. An example of this is when the player encounters the Nemesis on the bridge,the game then gives options - do you jump into the water or push the pursuer off?
In the newest Resident Evil games such as Resident Evil 4 and Resident Evil 5, QTEs play a larger role and now, depending on what you're trying to evade, if you fail the QTE your character will die instantly.
In Resident Evil 6, QTEs are much easier to complete, specially if one is using the Breakout Skill and, unlike the two previous games, the prompts will always be the same unless you choose a higher difficulty. They also repeat a lot, for instance, in the beginning of Jake's Chapter 4, the two QTEs in the Motorcycle stage will always be the same no matter what. Additionally, QTEs in Resident Evil 6 also serve as a way to open doors, counter enemy attacks, use certain objects and even to drive vehicles.
In Resident Evil 6, all QTEs will be automatically completed even if the player fails them by turning on the "auto action button" option in the Game Settings menu. Although if the Amauter difficulty is selected, all QTEs will be successful even if that option is turned off.