Land surveys are made to establish boundaries of land areas by setting corner markers or monuments, to ascertain coordinates of these corners, and to obtain boundary and area information required for record-deed descriptions and for plotting parcels of real property. Property surveys are accomplished with a degree of precision depending on the value of the land involved, and permanent visible and recoverable monuments are set at the corners. These markers are desirable for public record and to ensure correct title for the rightful owner of the land. In addition to surveying techniques, land surveyors must also be knowledgeable in property law; registration of practitioners is usually required by law.