Maps use symbols to show places and things on Earth.
A map is a reduced representation of a particular area,state,country or simply saying some space.It has it's own limitations and hence very difficult to give the exact data.To overcome the short coming in the accuracy they are given a system where we use symbols to give details about the object,distances,features or any such information about that particular area or zone.This helps the users to understand the MAPS and take advantage of the data and make full use of it to fulfill the need.