Control signs are the most important regulatory signs because they decide who goes first. Permanent control signs are red and white, sometimes with black symbols, and unlike other families they come in a variety of shapes so you can recognise them even from behind.
Stop (red octagon). Come to a complete halt in line with the sign or before the stop line and move off only when it is safe. At a 3-way or 4-way stop the vehicle that stopped first proceeds first; if two stop at the same time, the vehicle on the right goes first and a vehicle going straight has priority over one turning across its path. A stop sign with a left-turn yield plate lets you turn left without stopping if it is safe, but you must still stop if going straight or turning right.
Yield (inverted red-bordered triangle). Give way to all cross traffic and to pedestrians crossing or waiting to cross; you only need to stop if it is necessary. Variants add a pedestrian plate (yield to pedestrians on the crossing) or a circular arrow (yield at a traffic circle or mini-circle to vehicles already in the circle).
No entry (white disc, red border, red bar) means no vehicle may enter at any time, typically at the exit of a one-way street or off-ramp. One-way signs are red rectangles with a white arrow: travel only in the direction shown. Yield to oncoming traffic (red up arrow, black down arrow) marks a single carriageway shared by both directions. The pedestrian priority area diamond limits vehicles to access only and 15 km/h, and the Stop/Go board at roadworks must be obeyed like a stop sign.
Remember the order of authority: a traffic officer first, then traffic signals, then road signs, then road markings.