What is International Date Line? Describe the use of this line.

A zigzag line at roughly 180° meridian is the line which is internationally adopted as International Date Line or IDL. On either side of this line, a difference of whole day is observed. This is because the earth completes one rotation on its axis in 24 hours as it rotates from west to east.

International Date Line is for the convenience of those travelling round the world in order to avoid any confusion.