The use of rare earths has received great attention due to the increased consumption of such metals in the electronic industry, in the fabrication of catalysts, alloys and high-tech materials in general. It can be expected that rare earths production and consumption by developed countries will increase, as these metals will be more widely applied in the industry and their market is expected to expand both in volume and monetary terms. In the present work, the technological and environmental aspects of the rare earths have been reviewed and investigated, starting from resources, availability, industrial applications and trends on international markets.