For centuries Paris has been one of the world’s most important and attractive cities. It is appreciated for the opportunities it offers for business and commerce, for study, for culture, and for entertainment; its gastronomy, haute couture, painting, literature, and intellectual community especially enjoy an enviable reputation. Its sobriquet “the City of Light”, earned during the Enlightenment, remains appropriate, for Paris has retained its importance as a centre for education and intellectual pursuits. In its location on the western side of Europe and in a plain relatively close to the sea, Paris benefits from the balmy influences of the Gulf Stream and has a fairly temperate climate. The weather can be very changeable, however, especially in winter and spring, when the wind can be sharp and cold. The temperature drops below freezing for about a month each year, and snow falls on approximately half of those days. The city has taken measures to decrease air pollution, and a system of water purification has made tap water safe for drinking.