We review briefly the consequences of proton‐proton (pp) collisions in extragalactic radio jets—a problem which we have been tackling since 1982. Effort was made to answer the following questions: Can the results of pp collisions in the jets account for the observed radio, optical and gamma ray emission from the jets of extragalactic radio sources (EGRS)? What is the nature of these relativistic protons? What is the origin of the central gaps which are observed in EGRS?