John Muir was a Scottish-American naturalist, author, environmental philosopher, and early advocate of preservation of wilderness in the United States. He is often referred to as the 'Father of the National Parks' and was an important figure in the development of the modern environmental movement. Muir was a West Coast naturalist who explored and wrote about the Sierra Nevada mountains of California. He was also a passionate advocate for the preservation of wilderness areas, and his writings helped to inspire the creation of the National Park System in the United States.