A scientific introduction RPC: where we are and where we are going

A large number of papers and reports that have been published after the Napoli RPC97 workshop show an impressive progress in improving the RPC performances and extending their use to new fields of application. This talk is an attempt to summarize the state of the art at the beginning of the present workshop as an introduction to the new results that will be presented. A discussion about the scaling of operating voltage and time resolution with the gas gap size will also be presented.