An Introduction to Pomerons

This talk is an attempt to clarify for experimentalists what do we (theorists) mean when we are saying “Pomeron”. I hope, that in this talk they will find answers to such questions as what is Pomeron, what we have learned about Pomeron both experimentally and theoretically, what is the correct strategy to study Pomeron experimentally and etc. I also hope that this talk could be used as a guide in the zoo of Pomerons:“soft” Pomeron, “hard” Pomeron, the BFKL Pomeron, the Donnachie Landschoff Pomeron and so on. The large number of different Pomerons just reflects our poor understanding of the high energy asymptotic in our microscopic theory QCD. The motto of my talk, which gives you my opinion on the subject in short, is: Pomeron is still unknown but needed for 25 years to describe experimental data . This is a status report of our ideas, hopes, theoretical approaches and phenomenological successes that have been developed to achieve a theoretical understanding of high energy behaviour of scattering amplitude. I HIGH ENERGY GLOSSARY In this section I am going to define terminology which we use discussing high energy processes. Most of this terminology has deep roots in Reggeon approach to high energy scattering and it will be more understandable after my answer to the question:“what is the “soft” Pomeron”. Although I cannot explain right now everything, I think, it will be very instructive to have a high energy glossary in