The two most significant free travel areas in Western Europe are the Schengen area, in which very little if any border control is generally visible, and the Common Travel Area (CTA), which partially eliminates such controls for nationals of the United Kingdom and Ireland. Between countries in the Schengen Area, and to an extent within the CTA on the British Isles, internal border control is often virtually unnoticeable, and often only performed by means of random car or train searches in the hinterland, while controls at borders with non-member states may be rather strict.