LEED certification creates green, third-party verification that a building, house or community or neighborhood was designed and built using strategies purposed on achieving high performance in essential areas of human and environmental development: sustainable site development, water use reduction, energy efficiency and energy performance improvement, sustainable material selection and improving indoor environmental quality. There are various differebt of LEED rating systems available to meet the needs of different development and project types. Every LEED rating system consists of prerequisites and credits. Prerequisites are essential and mandatory elements, or green building system that must be included in any LEED certified green building project. Credits are optional elements, or strategies that projects can elect to pursue to gain points achieing LEED certification.