Internet users in India have reached 37 million this September - up from 33 million in March 2006. During the same period, the number of "active users" moved up to 25 million in September from 21.1 million in March."Active User" is an internationally-accepted and widely-used category to define users who have used the Internet at least once in the last 30 days. The study - jointly conducted the Internet and Mobile Association of India (IAMAI) and IMRB International - estimates the Internet user base is likely to cross the 40-million mark by March 2007.The numbers are a result of an "offline" survey carried out in India to estimate the "ever user" and "active user" categories. The survey did not include rural areas.According to the findings, youth are the main drivers of internet usage in India. College students and those below the age of 35 are the biggest segment on the Internet. Besides the youth, Internet-hungry small towns are further fuelling the growth.As per the survey, smaller metros and towns are increasingly embracing the Internet evolution and are pushing growth from below. Smaller cities and towns have shown a whopping 142% YoY growth and now account for 25% of all Internet users.Subho Ray, president of IAMAI, said: "Although there is a marginal revision of the earlier IAMAI number for the year, given the rapid growth of Internet business and government's massive e-governance programme, it was time to look into the numbers more stringently. This will help better business decisions on part of the industry as well as better resource planning by the government."Mohan Krishnan, vice president and country manager (eTechnology Group) of IMRB, said: "The next round of growth will be driven by new and innovative applications such as blogs, P2P, video on demand and online gaming while the old favourites such as email, chat and IM will drive first time users to the medium."