Friction isn't always bad, but when engineers try to avoid or reduce friction, it is because of the energy lost due to friction.
botch
Friction can be either good or bad depending on where it is. Friction between parts that are meant to stay put is a good thing, friction between parts that are supposed to move is a bad thing. Tires for instance are meant to roll along the road, not slide. Here, friction is good. But then you cone to the hubs. In here, the wheel has to move around the axle. Here, friction is bad. Here, friction will turn effort that would otherwise have gone into moving the bike forward into heat, which is no use to the rider at all.
bad friction is when 2 things rub together .
In situations where you want to create heat or dissipate kinetic energy, friction is usually a good thing. Friction when rubbing your hands together creates heat, which you appreciate, and friction between your brake pad and brake disc slows down your car, which is also a good thing. In situations where you want to maintain kinetic energy or minimize heat, friction is usually bad. Air friction slows down a glider, limiting its range, and mechanical friction in a car rolling on a flat surface causes it to stop without the brakes being applied.
Yes. Internal friction exists.
Friction is good because it provides traction. Friction is necessary for people to stand, or for vehicles to accelerate or break. Friction can also be used to convert kinetic energy to heat or electrical energy. Friction can be bad because kinetic energy is can be lost to friction.
if it is an advantage then it can't be bad
It depends what you want to do with it. Friction generates heat, which can be good (if you are cold), or bad (if you are not). Friction slows down movement, which can be good (if you are about to crash into a tree with your car), or bad (if you need high performance in an engine for instance).
No friction is not always bad. In fact consider an example of running on wet floor. If there is too little friction it might cause you to slip and slide.
wheels overcome friction
it wears things away
Without friction, cars wouldn't work.