i have been meditating frm an year now...i experience muscle twitching all over my body...especially very much between the eyebrows..secondly i want to knw what is samadhi?.
Let me answer your second question first: What is samadhi? Samadhi is the state of oneness with God. If you are interested in looking into this more deeply, I highly recommend The New Path, which is available for reading without charge online. The whole book is marvelous, and I would recommend starting at the beginning and reading through it for an excellent introduction to the spiritual path. Samadhi is referred to throughout the book, but I think you will find the most satisfying explanation if you read Chapter 32.
About your twitching: This could possibly be due to carrying stress in the body. Perhaps it would help you to find a yoga postures class to help relax the body before you meditate. You mention that the twitching is especially between the eyebrows. Though I can’t at all be certain from such a short exchange, it’s possible that in your efforts to concentrate your mind at the point between the eyebrows that you are holding tension there.
Try beginning your meditation by inhaling deeply and tensing the body all over, including tensing the face. Then throw the breath out as you exhale and relax the body completely. Try repeating this exercise three times. After the third time, focus your mind on moving through the body and relaxing each body part, working your way up the body from the feet to the top of the head. Try to feel space in the various parts of the body, and then forget about them.
Devoting a little more time to focusing on physical relaxation might help your meditation. Swami Kriyananda said that in the beginning of meditation, the biggest obstacle is physical tension.
May you find increasing joy in your spiritual life,