Sampradaya
In Hinduism, a Sampradaya is a tradition of disciplic succession serving as a spiritual channel and encompassing a common philosophy embraced by many schools, groups, or guru lineages (called parampara). By receiving initiation (diksha) into a parampara by a living guru, one automatically belongs to its proper sampradaya. Initiation is the only means by which one can become a member of a sampradaya; one cannot become a member by birth, as is the case with Gotra, a seminal, or hereditary, dynasty.
There are four Vaishnava sampradayas according to Padma Purana quoted in Böthlingk Sanskrit-Sanskrit dictionary, entry Sampradaya, Sabda-Kalpa-Druma Sanskrit-Sanskrit dictionary and Prameya-ratnavali 1.5-6 by Baladeva Vidyabhushana:
sampradaya vihina ye mantras te nisphala matah
atah kalau bhavisyanti catvarah sampradayinah
sri-brahma-rudra-sanaka vaisnavah ksiti-pavanah
catvaras te kalau bhavya hy utkale purusottamat
ramanujam sri svicakre madhvacaryam caturmukhah
sri visnusvaminam rudro nimbadityam catuhsanah
"Unless one is initiated by a bona-fide spiritual master in the disciplic succession, the mantra he might have received is without any effect. For this reason four Vaisnava disciplic successions, inaugurated by Sri, Lord Brahma, Lord Rudra, and Sanaka (one of the four Kumaras), will appear in the holy place of Jaganatha Puri, and purify the entire earth during the Kali yuga (current age). Sri chose Ramanuja to represent her disciplic succession. In the same way Lord Brahma chose Madhvacharya, Lord Rudra chose Visnu Svami, and the four Kumaras chose Nimbaditya (Nimbarka)."
One example of a Vaishnava parampara is the Brahma Madhva Gaudiya Vaisnava Sampradaya.
There are also Shaivite sampradayas, for example, the Nath and Nandinatha Sampradayas.