Tire tread design varies quite a bit in appearance, but most passenger vehicle tires are designed to channel water away from the contact patch to achieve the most grip.
Slick tires have no tread, so they are very good at gripping dry paved surfaces, but have no way of channeling water away or clinging to loose surfaces, so they are a very purpose-built tire design for dry, paved surfaces. Slick tires are not street legal in most countries, due to how unsafe they are in wet road situations.
Slick tires often have wear indicator holes in the wear surface that allow for measurements to be taken before and after. The difference between the before and after measurements would tell how much that location has worn out, allowing race teams to make adjustments to the tire pressure and mechanical set-up for improved grip and/or tire wear.
Off-Road Tire Tread
Tire treads designed to go off road have treads which grip loose surfaces well because the material can get between the threads, and the force of the wheel pushing the material together gives the tire something to cling to.
Snow Tire Tread
Tires designed to perform well in snow are similar in concept to off road tires, but have additional gripping points due to ice being a very low-friction surface. The rubber compound is carefully considered because in the snow, the tire won't heat up (which softens the rubber in other tires, providing more grip) anywhere near as much as tires in other conditions.
How to Read Tire Tread Wear Patterns
Tires tend to wear out differently if the suspension is in poor condition, damaged, or adjusted incorrectly. Tire pressure also plays a role in uneven wear, and is the easiest to diagnose; wear on the inner portion of the tire tread means the pressure has been too high, and wear on the outer edges of the tread mean the pressure has been too low.