Meditation or Dhyana is a state of being.  We enter a state of meditation  when we focus our mind on one object- pratyahara. The object can be the breath, a mantra or image. When we focus on the object, the fluctuations of the mind start calming down, to become still. Therefore, our mind becomes peaceful and present. There´s many tecnhiques of meditation that suits each individual tastes but the goal is always the same- self realization. Become present and aware.