What is LEED in green building system?

LEED (Leadership in Energy and Environmental Design) is an internationally recognized green building certification system,  providing third-party verification that a building or community was designed and built using strategies aimed at improving performance across all the metrics that matter most: energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality, and stewardship of resources and sensitivity to their impacts.

I get the answer from http://www.bu.edu/sustainability/what-were-doing/green-buildings/leed/

and now I know about LEED , Thanks Mr.Shakeel

I agreed With the answer of  Mr. Alex Al Yazouri .

LEED (Leadership in Energy and Environmental Design) in energy savings, water efficiency, CO2 emissions reduction and more.

Leadership in Energy and Environmental Design

its Abbreviated for Leadership in Energy and Environment Design . Especially associated for the Design , construction , Maintenance for the Green Buildings

the definition for LEED is: 

1. LEED, or Leadership in Energy & Environmental Design, is a green building certification program that recognizes best-in-class building strategies and practices. 
2. To receive LEED certification, building  projects satisfy prerequisites and earn points to achieve different levels of certification.

There are numerous things that would go into it many are well suited in some regions but not as well in others. After picking a sight I would then consider building materials there are many including SIP's, Strawbale, ICF's, earthship home and many more I am partial to SIP's myself. I would consider geothermal heating, a cistern for collecting rainwater for use in flushing toilets is inexpensive when dealing with new construction, I would use a GFX system which is a type of drain water heat reclaimer. The house should be very well insulated with soy based foam or cellulose. The windows should be at least double pane with region applicable e-film coating. Orientation of the house is important both for solar applications and clerestory windows that with the proper roof overhang would let the sun in during the winter and be blocked in the summer. Any reclaimed wisely used building materials would be a plus. Aerators and ultra low flow shower heads throughout. Use of only no and low voc paints. All building materials should be sustainable choices. Here are some sites to look at, as this could go on for a while.