This chapter introduces environmental concepts and challenges, including climate change, biodiversity loss, scarcity of natural resources, pollution, as well as industrial disasters. It discusses the limits to growth, and ethical issues connected to preservation of natural resources. Biophysical or natural environment refers to the surroundings of an organism, and includes the factors that have an influence on its survival, development, and evolution. The built or modified environment typically refers to manmade structures or spaces – from gardens to car parks, from furniture and houses to entire cities. Economists have often focused on viewing the economy and the environment as a single interlinked system with a unified valuation system. Heavy extractive industries such as drilling for oil, coal mining, and stone quarrying involve processes that degrade the environment. The ecological systems services provided by our natural environment are the basis for economic development, social prosperity, and ecological well-being.