Aggressive climbing shoes are shoes with a downward curve, many times also with a twist towards the big toe.
This downward curve allows the climber to exert maximum power through their toes, allowing them to have more force and stability, and to be able to stand easier on bad foot holds.
Aggressive climbing shoes are also the popular choice for bouldering, since they tend to be less comfortable than neutral or flat shoes, which mean that climbing in them for a longer period of time could be quite painful, which makes them less popular for sport climbing. They are also a great choice for overhanging climbing as they tend to excel at gripping holds, allowing the climber to keep their body closer to the wall and to keep their feet on the holds.
Eventually, as the shoe is used more and more, the curve loses its shape, and the shoe become straighter.
