A visa to India is mandatory for foreign nationals visiting India unless they are coming from visa exempted countries. They are obtainable at the Indian Missions, Consulates, High Commissions Overseas. And also Visa on Arrival and electronic travel authorization has been avail to 180 countries as per the notification on February 2014, and expected to come into action from October 2014.
The visas are valid for the period issued. They range from a 15 day period to up to a six month period for tourists. They are valid from the date of issue and it is wise to start travel as soon as the visa is obtained to take advantage of the entire period of visa validity. Once obtained, visas can be extended in India, (depending on the application) at the local “Foreigners Registration Office” located in every major city in India.