Among the various Hindu philosophies, Kashmir Shaivism (Kaśmir Śaivism) is a school of Śaivism consisting of Trika and its philosophical articulation Pratyabhijña. It is categorized by various scholars as monistic idealism (absolute idealism, theistic monism, realistic idealism, transcendental physicalism or concrete monism.)
It is philosophically important to distinguish Kashmir Shaivism from the Advaita Vedanta of Shankara as both are non-dual philosophies which give primacy to Universal Consciousness (Chit or Brahman). In Kashmir Shavisim, all things are a manifestation of this Consciousness. This means that from the point of view of Kashmir Shavisim the phenomenal world (Śakti) is real, and it exists and has its being in Consciousness (Chit). In comparison, Advaita Vedanta holds that Brahman is inactive (niṣkriya) and the phenomenal world is an illusion (māyā). Thus, the philosophy of Kashmir Shaivism, also called the Trika, can be seen in contrast to Shankara's Advaita.
The goal of Kashmir Shaivism is to merge in Shiva or Universal Consciousness, or realise one's already existing identity with Shiva, by means of wisdom, yoga and grace.
"Kashmir Shaivism has penetrated to that depth of living thought where diverse currents of human wisdom unite in a luminous synthesis." - Rabindranath Tagore (9 May 1861 - 7 August 1941) Nobel Prize in Literature (1913).
Read more about Kashmir Shaivism: Origin, The Siva Sutras, Classification of The Written Tradition, The Revival of Kashmir Shaivism in The 20th Century, Contemporary Kashmiri Saivites From Kashmir