Samatha is method of training the mind for those who like to develop their concentration. Samatha meditation is concerned with producing a one-pointed mind.

One-pointedness is a concentrated state in which all the faculties and mental powers are focused and governed by the will-power and directed towards one point or one object. A one-pointed mind is a concentrated an unified mind. A one-pointed mind is the opposite of a distracted or scattered mind. Ordinarily our mental states are scattered in all directions but if the concentration is fixed on one object, then you begin to know the true nature of that object. The process of concentration gradually modifies the mental states until the whole mental energy converges towards one point.

What is the purpose of developing a one-pointed mind?

If you train your mind in this manner, then you will bring calmness and tranquility to the mind and you will be able to gather your attention to one point, so as to stop the mind from frittering away and wasting its useful energy. A calm mind is not an end in itself. Calmness of mind is only a necessary condition to develop insight. In other words, a calm mind is necessary if you want to have a deep look into yourself and to have a deep understanding of yourself and the world.