The ability to create a bounding box is useful for doing filter by BBOX queries. The coordinate systems of the data and the BBOX must match, so any BBOX creation function must be wrapped in the ST_SetSRID function. For that kind of query, the && operator, meaning intersects BBOX, is used. For example:

SELECT * FROM planet_osm_point WHERE way && ST_SetSRID('BOX(-500 6705000,1000 6706000)'::box2d,900913);  

This will return all the rows from the planet_osm_point table whose geometries fall completely or partially inside the defined BBOX. Note that this returns the complete geometries that share even the tiniest part with a BBOX. Clipping geometries to BBOX will be discussed in the next chapter.