From "Why Meditate"

We expect a lot of effort to improve the external conditions of our lives, but in the end it is always the mind that creates our experience of the world and translates this experience into either well-being or suffering. If we transform our way of perceiving things, we transform the quality of our lives. It is this kind of transformation that is brought about by the form of mind training called meditation.
SO, the primary goal of meditation is to transform our experience of the world.

According to Buddhism, the mind is not an entity but rather a dynamic stream of 
experiences, a succession of moments o consciousness.