Vaastu is actually the science of direction which combines all the five elements of nature. After combining it balances them with man and materials. These five elements are EARTH (Bhumi), WATER (Jal), AIR (Vayu), FIRE (Agni), SPACE (Akasha).It's main motive is interaction of various forms of best effect on a living person. It can be anything regarding a person in which it can bring the best in ourselves, for enhanced health, wealth, prosperity and happiness in an enlightened environment. Vaastu is universal, rational, practical and utilitarian like any other science. It is not at all related to any religion but a science.
Term shastra can be translated as "science,doctrine,teaching". Vaastu shastra also known as Vaastu Veda is a "science of construction and architecture".
The origin of vaastu shastra is a traditional Hindu system based on direction. It is basically applied in Hindu architecture for Hindu temples but also covers other area like poetry, sculpture, dance etc. Mamuni Mayan, the mythical sage is traditionally the foundation of vaastu.
Now, a number of western application have appeared in the market offering vaastu as an alternative to Chinese Feng Shui.