Write in brief:
Why is the IDL considered with respect to the 1800 meridian only?
The International Date Line was constructed in 1884 to change the date and time according to the global travelling. The crossing of the 180 ̊ prime meridians can result in the change of time zone. Thus some precautions have to be taken to avoid the confusions in the time zones. Thus the date and time may have to be changed to incorporate this. This has to be made by considering the Greenwich 180 ̊ prime meridian.