Work results in a change in energy?

[Dee08]

In my textbook and in a lot of other resources it says that the work done on an object is equal to the object's change in kinetic energy. I was under the impression that work is the change in total mechanical energy.
Also, if an object is being raised vertically upward, isn't the work done on the object equal to its gravitational potential energy?

I'm really confused! It would be greatly appreciated if someone could explain this concept to me :)

 

[vuellesse]

I think it is correct to say that the work is equal to the object's change in kinetic energy, if by work you mean the one of the net force on the object (which includes gravity).