Ans: The local times of different countries are different because of their location on the meridians. For instance, in India, there is a difference of One hour and 45 minutes concerning the local times of Dwarka in Gujarat and Dibrugarh in Assam. Therefore, it becomes a necessity to have a standard time by adopting the local time of certain meridians. Longitude 82 ½ degree E is taken as the standard meridian of India, and thus the standard time at this particular meridian is taken to be the standard time for the country, known as the Indian Standard Time (IST).