Second mates on ships are often seen engrossed with drawing lines and working on those multi colored, thick bundles of sheets kept nicely stowed in canvass covers in various shelves in wheelhouse or Navigational Bridge.
Few have even wondered how a trivial task such as drawing courses on those sheets can make him so engrossed with his work.
The fact is those conglomerations are popularly known as Charts and they happen to be the lifeline of ship navigation.
One cannot imagine navigation without charts.
They are classified on the basis of the regions where they are printed, published, and updated or because of regional hydrographic offices controlling generation, assimilation and update of information concerning them.