Nandi is the protector and gatekeeper, also the Vahan of god Shiva. He’s a sacred bull calf. Nandi got the divine knowledge of Agamic and Tantric wisdom taught by lord Shiva and goddess Parvati. Nandi used to sit in front of the Shiva because while meditating, shiva used to feel hot, so to avoid the burning, Shiva ordered Nandi to sit in front of him and blow some air towards him. It is good to put Nandi inside house or at the temple side where there is statue of lord Shiva. You can also put Nandi’s statue in a main hall as a showpiece.