Linked from
The 27 pages that link to Proton–proton chain, each with the reason it gives.
ProtonRelated: Protons initiate the fusion reactions that power Sun-like stars.
Main sequenceRelated: It supplies most of the energy in the cores of lower-mass main-sequence stars.
Red dwarfRelated: This reaction sequence supplies the energy radiated by red dwarfs.
Homestake experimentRelated: Its reactions produce the solar neutrinos Homestake sought to measure.
ProtiumRelated: Its initial fusion step involves hydrogen nuclei, chiefly protium in stellar matter.