Most things are affected by friction. There are two types of friction, kinetic and static. Static friction is the force that stops a thing from starting motion. If you were to push hard on a heavy block, it would not move. Kinetic friction is the force of friction while the block is moving.
Friction is proportional to the normal force. It can be expressed as

where u is an experimentally determined constant dependent on the materials in question. It can be inferred from this that if the gravitational force is in someway reduced friction is lessened. Friction always opposed the direction of motion. Static friction has a larger coefficient then kinetic friction That means that once an object has started to move, it takes less force to continue to make it move. Static friction will counteract the force attempting to move the object exactly until the limit is reached, which is the coefficient of static friction multiplied by the normal force.

Suppose you have an object on an incline plane of 30 degrees that weighs 10 kg and that the coefficient of static friction is .4. We want to know if there is enough force to move the block. First, it is important to notice the unusual reference frame that has been chosen. It makes the most sense to use this reference frame as the motion, the frictional force and the normal force are parallel or perpendicular to this reference frame. Since the gravitational force is not, it must be found and then resolved. The gravitational force is found to be 98 Newtons. Through geometry, it can be shown that the angle between the y-value of the vector and the magnitude of the vector is equal to the angle of inclination. Thus it can be shown that in this case

Though, previously it was stated that the normal force counters all of the gravitational force, this is not always the case. The normal force will always be perpendicular to the horizontal. This means, that any part of the gravitational force parallel to the horizontal will be disregarded. Thus the normal force in this case is equal to 85 N.

Using the coefficient of static friction, we can determine that the frictional force to be

.

There is no y force as the normal force and gravity cancel out. As the force due to gravity in the x direction is greater then the static frictional force, the block will start to slide.