what is a schengen agreement?

Answer 1

The Agreement was signed near the town Schengen in Luxemburg by several european countries. It aims at a common border control of the outer borders, and the removal of any border checks between members of the agreement.
For more information and a map of the Schengen Countries look here: http://en.wikipedia.org/wiki/Schengen_Agreement

Answer 2

It is an agreement voted on in the town called Schengen.
There to decide on it where the people of several European countries and they decided to have better border control on the outside borders of this area and stop checking on the borders between the countries involved.
At the time there where seven countries but since more countries have joined, inside the European Union and outside.
Now all those countries are known as the Schengen countries.

http://www.eurovisa.info/SchengenCountries.htm