EPSG database? What is EPSG?

EPSG stands for European Petroleum Survey Group.
This group created the EPSG database: a collection of definitions of coordinate reference systems and coordinate transformations, which may be global, national or local in application.

Each entry in the EPSG database has a unique code (4-5 digit number). Hence it allows to search for coordinate related information solely based on EPSG codes.

Some examples:

• EPSG 4326 : Refers to the World Geodetic System 84 coordinate reference system;
• EPSG 6326 : Refers to the datum that is used with WGS84;
• EPSG 8901 : Refers to the Prime Meridian that passes Greenwich (UK);
• EPSG 7030 : Refers to the WGS84 ellipsoid;

More information about the EPSG database can be found at: http://www.epsg.org/