Vastu Shastra is principles of design, layout, measurements, ground preparation, space arrangement, and spatial geometry. The designs aim to integrate architecture with nature, the relative functions of various parts of the structure, and utilising geometric patterns, symmetry, and directional alignments.
Vastu Shastra is the textual part of Vastu Vidya - the broader knowledge about architecture and design theories from ancient India. Vastu Vidya is as old the Vedic period and linked to the ritual architecture. The emergence of Vastu vidya as a specialised field of science is speculated to have occurred significantly before the 1st-century CE. It is believed that every piece of a land or a building has a soul of its own and that soul is known as Vastu Purusha.
Vastu shastra represents a body of ancient concepts and knowledge to many modern architects, a guideline. The square-grid mandala is viewed as a model of organisation, not as a ground plan. The ancient Vastu shastra texts describe functional relations and adaptable alternate layouts for various rooms or buildings and utilities, but do not mandate a set compulsory architecture. The basic theme is around core elements of central space, peripheral zones, direction with respect to sunlight, and relative functions of the spaces.