There is famous Rigvedic Verse that says "Ekam Sat " that is "There is one Being ,the sages call Him by many names." The God (Parmeshwar) has three deities who carry on the world .This is Known as Holy Trinity.
Brahma- the creator, Vishnu-the perpetuator of life and Shiva (Mahesh ) -the purifier and perpetuator of good and destroyer of evil. Rig Veda refer Shiva as Rudra as in its following verse . "We Worship Tryambaka (Rudra) , Who spread Fragrance and Increases Nourishment , May He release me ,like the cucumber from its stem , From Mortal Life , But not From Immorality . "(Rig Veda Mandal VII Sukta 59 and Mantra 12) The Yajurveda describes Shiva as ascetic warrior Whose robe is of Deer Skin and He carries Trishul . According to the verse Satyam, Shivam ,Sundaram ,the life is described as having three facets Truth (Satyam), Good (Shivam) and the Beautiful (Sundaram)

Shiva is a living God
The most Sacred and ancient books of India, the Rig Veda narrates His presence in the hymns. Vedic myths, rituals and even astronomy testifies to His existence from the dawn of time .The Mohindaro and Harapa findings confirm Shiva worship in the ancient India. According to the older scriptures, He has three places of His residence. One is Kailash Parvat another is Lohit Giri under which Brahamputra flows and third is Muzwan Parvat .