A Sampradaya is the name given to a Spiritual succession or lineage within a particular Hindu denomination.
To recieve initiation (Diksha) into a Parampara or Guru lineage allows one to be officially made a member of that Sampradaya to which his or her guru lineage belongs.
Each Sampradaya has its own spiritual lineage, philosophy, monastic communities, literature, pilgrimage places and temples etc although sharing a wealth of heritage, culture and belief with other schools which under a Sect they find their greater expression of tradition and ideologies. In order to help elucidate the concept of Sampradaya there are four main denominations within the Hindu Religion:
Vaishnavism - who worship the Supreme God as Vishnu (also called Narayana)
Shaivism - who worship the Supreme God as Lord Shiva (also spelt Siva)
Saktism - who worship the Supreme as the Divine Mother, Sakti or Devi.
Smartism - Liberal Hindus who worship all other Hindu Gods as valid manifestations of the Divine.
Within each denomination there are numerous sub-sects or schools called Sampradayas.
Within Vaishnavism these Sampradayas include:
Sri Vaishnavism Sampradaya - Whose members adhere to the teachings and lineage of Ramanuja
Dvaita or Brahma Sampradaya - who follow Madhva
Ramanandi Sampradaya - Who follow Ramananda
Sri Swaminarayan Sampradaya - who follow Swaminarayan
Pushtimarg Sampradaya (Rudra Sampradaya) - who follow Vallabhacharya
Kumara Sampradaya - who follow Nimbaraka
Gaudiya Vaishnavism (which includes the International Society for Krishna Consciousness or Hare Krishna Movement) - follow Chaitanya Mahaprabhu