How to replace turn signal bulb for Audi A4 (B7)

Car turn signals or blinkers are twinkling lamps, mounted two or more at each side of the vehicle. These lamps are activated by the driver to notify others, that the movement direction of a car is going to be changed. It's very important turn signals are used whenever necessary, in order to improve alertness of the other road users and avoid traffic accidents. For the same reason, all directional signals have to be functioning properly. The most common cause of a defective turn indicator is an idle bulb, that the driver is able to notice straight off: when failing side turn signal is activated, corresponding fascia indicator's blinking rate will be higher, even though only one bulb has burned out.