The meaning of the Rudrabhishekam is to convey that everything is Shiva, and is contained within the Shiva Tattva. There is nothing beyond the Shiva Tattva.
It is said: that which moves, and that which is steady and immobile – is the Shiva Tattva. That which is awake and that which is dormant or asleep – is also the Shiva Tattva. That which is greatest, supremely intelligent, and that which is the smallest – is the Shiva Tattva. In the Rudram chanting there is a verse which says, “Namo jyeshthaaya cha kanishthaya cha. Namo dhundhubhyaya cha hananyaya cha”. It means Salutations to that (Shiva Tattva) which is the greatest and the smallest; That which nurtures and That which destroys and dissolves everything – is also the Shiva Tattva. Shiva Tattva is both the unmanifest, and the manifest in all forms of Creation.
Rudrabhishek is believed to be an ancient chanting which came from the Akasha (space). When the ancient sages sat in meditation, they heard these sounds (of the mantras), and they started transferring to other people what they heard and that is how the Rudrabhishek was transferred to people.
The effect of Rudrabhishek is, it creates positive energy and removes negative vibrations. The main thing is the vibration, that is it. It’s the vibration of the chants that is more important than the meaning. When Rudrabishek happens, nature flourishes; nature becomes joyful and happy.
Mainly, it creates more positive energy; more so when people are meditating.
Sri Rudram contains Namakam, Chamakam, Manyu Suktam, Purusha Suktam, Sri Suktam and Mantra Pushpam along with Laghunyasam from Krishna Yajurveda.
Rudrabhishekam Pooja is done to worship Lord Shiva in Rudra form. Rudra Suktham is chanted while performing the Abhishekam to the Shiva lingam. Lord Shiva is also known as Bholenath as he gets very easily pleased by the prayers of his devotes.
In this pooja, Shiva Lingam is bathed with panchamritam and water. All the eleven forms of Rudra are worshiped by using 11 types of abhishekam, Rudra Vilva Archana, Shiva Astotra and 11 types of Namaskarams are performed.