The physical act of crossing a border either at a border crossing point or another point along the border.
There are two broad types of agency, each with different characteristics and raising different issues. "Regulatory" or "traditional" agencies have a variety of specific roles, set out in their own legal basis, case-by-case (e.g. European Agency for the Management of Operational Cooperation at the External Borders - FRONTEX). Executive agencies are set up under a Council regulation adopted in 2002 with the much more narrowly defined task of helping to manage EU programmes (e.g. Education, Audiovisual and Culture Executive Agency - EACEA).