Friction is considered helpful during situations such as, but not limited to, preventing slipping between the shoes and the floor during walking, preventing skidding between tires and the road while driving, in brake pads where friction causes the vehicle to stop, and in order to grip things to hold them properly. In all of these cases, friction is important and very beneficial to completing the task at hand.
Friction is a resistance force that slows down or prevents motion. It occurs due to the interaction between two objects that move relative to each other. These objects can be solid, liquid or gas. Friction is the reason that unlubricated bike chains are harder to push and why devices with moving parts wear out with time. Friction is also the reason why these devices generate heat, like in the brake pads, and why it's possible to start a fire by rubbing two sticks together. Thus, in many cases where friction is trying to be reduced, lubrication is used or the surfaces are made to be as smooth as possible. In other cases where friction is helpful and needs to be increased, rougher surfaces or surfaces made of stickier material, such as rubber, are used.