dhyana yoga

Dhyana yoga is seventh limb of Yoga philosophy. It is for the intention of knowing the truth and revealing the hidden facts. Dhyana Yoga concentrates upon a point of focus, according to Patanjali it is the contemplation and Meditation of spiritual things. Not only for this but also for concentrating in our day to day activities performance of Dhyana yoga is essential.
As Swami Gitananda explains in “The Ashtanga Yoga of Patanjali”:

“Meditation is a most misunderstood word. It has come to mean for many, simply sitting with the eyes closed, or the repetition of a mantric sound over and over.
According to Patanjali, meditation is the seventh step of the eight limbs of Ashtanga Yoga. Therefore it cannot be something as simple as ‘sitting with the eyes closed’. It must be something much more profound, much more elevated one— and indeed it is!
Yet in modern times… one often encounters such comments as ‘meditation is good therapy’, and ‘my meditation has become boring’. … If meditation was such a mundane activity with such a mundane purpose as a cure for dejected and bored minds, why has the sage [Patanjali] put it as the penultimate step of a long and arduous climb?”

  Therefore dhyana Yoga is a continuous overflow of concentration, whereby very little ‘sense of self’ remains. At this level, it becomes increasingly more difficult to use words and the reasoning, conscious mind to describe the experiences of yoga. After all, the state of meditation, by its very nature transcends our material human experience and everything that is related to it. Dhyana yoga is therefore a person being one pointedness.
  In dhyana yoga we revolve only around the chosen matter mentally and at the same time deepening our process of concentration. Aim of dhyana yoga is to remove all senses from different matter of interest and focus on one object. It finally produces a state of tranquility and well cleansed subconscious, enhanced concentration and mind control.