The standard meridian of India is 82°30E. It passes through Mirzapur, a city in the state of Uttar Pradesh. The standard meridian is a longitude that determines a standard time for the whole country. The local time of places differs from one place to another, and there is a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam. Hence, it is necessary to adopt the local time of some central meridian of a country as the standard time for the country. The longitude of 82°30E is considered as the standard meridian for India, and the local time stated or mentioned at this meridian is considered as the standard time for the whole country. This is called the Indian Standard Time (IST).