Roll stabilizer in dark blue color
Controls the roll of the car from side to side and helps stabilize the car during cornering.
Weight transfer during the roll (left corner)
Weight transfer during the roll (right corner)
When both wheels are on the same level, the anti-roll bar does not affect the suspension motion. When one wheel is riding on a hump, the anti-roll bar will be twisted and transfer the force to another wheel to push it down, so the car body will remain balanced. The thicker the bar, the more anti-roll ability it has.
Based on the above description, you might be surprised to find out that anti-roll bar can introduce even more roll when the car is subjected to cornering force. Nevertheless, such impression is actually incorrect.
When body roll occurs due to cornering, the outside wheels are compressed, hence the anti-roll bars will push the inside wheels away from the body. Does this action result in even more body roll ? No. Because even without the anti-roll bar, the inside wheels will also keep in contact with the ground (due to weight of the car and the expansion force from springs), thus are pushed far away from the body (don't expect them to hang in the air!). In other words, the anti-roll bar doesn't alter the natural movement of the inside wheels.
Typical Anti Roll Bar
On the contrary, the twist torque of the anti-roll bar always tries to fight against the compression in outside suspension. Therefore it also reduces body roll.
The advantage of anti-roll bar is very clear - it suppresses body roll on bump or during cornering, but does not deteriorate ride comfort in straight line.
A stiff stabilizer makes the car respond well to sharp turns. Car feels more stable. Downside to that is if stabilizers are too stiff, it reduces weight transfer to the outside tires, reducing grip during cornering and causes understeer or oversteer. Softer allows the car to lean into the turn giving greater grip. But too soft, causes the car to be unresponsive.
If car understeer too much you need to reduce front stabilizers or likewise increase rear stabilizers. Make the front stabilizer softer than the rear to reduce understeer.
Lower right (rear suspension) and left (front suspension) type of antiroll bars is basicaly the same as one on the upper picture
Forward engined cars exhibit a slightly different response to the above; you want a higher front stabilizer setting than the rear. This will have an affect of reducing body roll of an forward engined car, keeping both tires firmly on the road rather than shifting all the weight to the outside tires and reducing grip.