The Hatha Yoga Pradipika is regarded as one of the three classic Yogic texts along with the Gheranda Samhita and the Shiva Samhita. This 15th century text was written by Swami Svatmarama, and is said to be the oldest surviving text about Hatha Yoga. This text has been translated into many languages, including English.
Chapter 3 Here he discusses various mudras which affect various parts of the body, and are meant to prevent disease and delay old age. Many of these exercises have symbolic as well as physical importance. These mudras are a way of focusing the mind and body. He talks a lot about kundalini and says that the main purpose for practicing the 10 mudras is to awaken the kundalini.