EU visas

A friend of mine is going to a European country. When one applies for a visa for one European country, is it valid for the whole EU? Can one apply for an EU visa?

Only the “Schengen Agreement” countries. Which is the EU plus a few other countries minus the UK and Ireland. I believe a visa for one of these countries is valid in all the others.

Thanks a million BFN.

Here is some info about it: