Road markings are as important as road signs. They control traffic flow, guide lane discipline, and mark safe and unsafe areas. The examiner is constantly watching whether you respect road markings and adjust your driving accordingly.
White lines mark lanes and road edges. A single continuous white line along the centre of the road means you must not cross it unless you are turning into a property or side road. A broken white line means you may cross it to overtake if it is safe. Double white lines (one continuous and one broken) mean you must not cross the continuous line, but traffic coming the other way may cross the broken line to overtake you. Two continuous white lines mean no one may cross.
Yellow box junctions are marked with criss-cross yellow lines. You must not enter a box junction unless your exit is clear. The only exception is when you are turning right and your exit is blocked by oncoming traffic: in that case, you may wait inside the box. Entering a box junction when you cannot clear it is a serious fault.
Stop lines are thick white lines at junctions and traffic lights. You must stop at a stop line when required. At traffic lights, the line is often accompanied by a solid white stop box. At junctions without lights, a stop line with a triangular give way sign means you must stop if traffic is approaching.
Bus stop clearways are marked with broad yellow lines at the kerb. During operating hours, you must not stop or park in these zones. School keep clear zigzag lines work the same way: no stopping or parking during the times shown on the signs. Ignoring these markings is a serious fault.