Vastu in Sanskrit means nature , a surrounding or environment.The word "Vaasthu" came from Vasthu , denoting anything existing such as house, shelter,building etc.
Ancient sages of India laid down several principles for constructing buildings taking advantage of the nature,the Pancha Bhootas namely Earth,Space,Air,Fire and water,gravitational and magnetic effects and rotational influences of Sun,Moon,Earth and other planets on the life in Earth with a view to bring balance and harmony between man, nature and his buildings and thereby ensuring peace,prosperity,and happiness.
Vaastu is such a vast field which really needs specialisation if someone want to study it.
Shop No. 3, C Block Shopping Center,
Vivek Vihar - I, Delhi - 110095
Web : http://www.sereneinteriors.com/vastu-shastra.html