One of the most esoteric parts of yoga practice is the use of Mudras. Literally, a Mudra is a sign or a seal for energy flow (prana). It is used to increase awareness and concentration. Mudras are influenced by cultural tradition as well as by anatomical considerations. While many of what we consider Mudras today are hand gestures, if you go back to the oldest sources, gazes, and other sorts of things fall in this category. In the Gheranda Samhita bandhas or locks are considered in the same section of the book, as well as some other techniques I cannot even imagine any modern yogi practicing, or imagine having any conceivable benefit. (Like cutting the frenulum below the tongue so one can pull the tongue back inside the mouth to lick the place the nose drains into the oral cavity...I mean, what?) But, I suppose, before judging some of what seem like bizzare practices to me I should flip through the latest edition of Ripley's Believe it or Not, with its pages of people who embed needles in their skin, or pull cars with their eyelids. The body has always been a canvas for artistic expression and personal exploration.
Actually you see similar hand movements and gestures in various dance forms. Think of Hula in Hawaii, in particular the pre 19th century hula, without western influence. Some of the Hulas were performed for the chiefs, some for the gods and had a highly spiritual component, performed with movement, hand gestures and chants (though most of the hand movements referred to nature or human emotion). Both classical Thai dance (which seems to be influenced by Indian) and Indian classical dance use hand gestures. As the Natya Shastra says “Where the hand is, the eyes follow”. The gestures become a poetic way to express meaning. They can stand for anything from a tiger, to herosim, to a flag.
The next time you go to an art museum and look at a collection of Hindu or Buddhist sculpture notice the very careful placement of hands. These are also mudrahs. For example, one part of the story about the Buddah is that when he was in meditation nearing enlightenment a demon came to try to get him to move, so he would not become enlighened. The demon brought a lot of friends to stand for him, and when he asked the Buddah who stood for him, the Buddah (or rather Siddhartha, as he was not yet the Buddah if we are going to be precise) touched the earth itself, which spoke for him. Notice the Mudra of witness, bhumisparsa mudra: right arm draped over the right knee with palm in and fingers of the left hand on lap palm up. The gesture of touching the earth suggests steadfastness, or we might say courage of conviction. One can think of many instances where humans symbolically touch the earth, such as a sailor touching the earth upon landing. It signifies a connection, and a connection that underlies our humanity.
I personally only use three or four Mudras in my practice. I do not think it is very common to use more than that, with the exception of schools in traditions like Kundalini. For example, I really like the Jupiter Mudra, with fingers clasped, index fingers pointing up, and thumbs locked when I take a standing half moon.
The most common one, that is used in most classes, though is Anjali, also called sometimes referred to as Namaste, or prayer posture. The hands are brought to the level of the sternum, touching with thumbs in (if you want a more detailed and precise description of the Mudrah, and the placements can be described in quite precise detail, you should be able to google one, I would think). The word prayer is of course weighted with meaning. But, although it does refer to an acknowledgement of spiritual center (Namaste usually is translated as something like 'that which is divine within me greets/bows to that which is divine within you) how each person understands the nature of the sacred is an individual one. It also in pointing inward to the heart underscores the importance of love and connection, and the central place that takes in our lives, and how important a gift that is. There is quite a lot of meaning packed into that gesture, so these points really just are a few of the parts that seem meaningful to me.
The use of hand gestures is almost universal. In some cases they are simple: the hand held up palm out to signify stop. In some cases, like the mudras we have talked about, they can be very complex. But remember that the hand is one of the most amazingly complex parts of the human organism. It is always fascinating to watch a person who plays well play an instrument, or paint a picture. Even the way a good masseuse uses their hands has poetry and music in it. You might enjoy Frank Wilson's book “The Hand” if you are interested in thinking further about this. And the next time you bring your hands together in Namaste allow yourself to feel the connection that simple hand movement allows between body, and mind, and spirit.