Priority Rules and Right of Way
Belgian priority rests on a hierarchy: police instructions, then traffic lights, then signs and markings, and finally the default rule. The default rule is right-hand priority: at an intersection with no signs, no markings and no lights, you give way to vehicles approaching from your right. This applies in built-up areas and outside them alike, and it surprises foreign drivers who expect a main road to keep priority.
Know the exceptions. Leaving a private driveway, a garage, a parking area, a petrol station or a field track, you yield to everyone. Reversing, turning left across oncoming traffic, and entering a roundabout marked with give-way lines all require yielding. Trams generally have priority over other traffic unless a sign says otherwise. Pedestrians already on a crossing or clearly intending to cross have priority; at an intersection without crossings, a pedestrian crossing the road you are turning into has priority.
Traps. Questions often place a give-way line on your side but a priority sign for the other road, or show a small side road joining a main road with no sign at all, where right-hand priority applies. Another classic: a vehicle coming from the right that is itself emerging from a car park does not have priority.
Rule of thumb: "no sign, no light, no marking means the right-hand rule." Worked example: you approach a T-junction; the road from the right has a give-way line painted. That line is their sign, so they yield to you even though they are on your right. If the line were absent, you would yield.