Introduction to triggering on vertices: past and future

Triggering on vertices has demonstrated to be very effective to select events having short lifetimes like in charm and beauty physics. These type of triggers are today proposed for many experiments to study B-physics, or to tag events in experiments looking for top or Higgs particles. In this introductory review on vertex triggers we present the most significative results from the past and introduce some of the proposals for future experiments. Comparisons of the trigger performance and the trends for the future are discussed.