How do Buddhists use mudras?

This is a practice question. I know both Mahayana buddhists and Vajrayana buddhists use mudras. In the former they show up in inconography, and hand resting positions while meditating, in the later it's part of elaborate rituals. How are mudras used in lay and monastic practice in Mahayana? Outside of being a step in larger rituals, how are mudras used in lay and monastic practice in Vajrayana?