Instagram on Wednesday said its user base in India has doubled over the last year. The social network that lets users post photos and videos, has 400 million monthly active users globally but it didn't reveal how many of them are from India. What Instagram did share is that people from the 18-24 age group are the most active on the platform. "Instagram has gained immense popularity and people are using it to express themselves. Our monthly actives in India have more than doubled over the past year (as of September 2015) and the momentum continues to build," Facebook India MD Kirthiga Reddy said at an Instagram press event in Delhi. Among the last 100 million to join Instagram, more than half live in Asia and Europe, Reddy said. In 2012, Facebook had acquired Instagram for $1 billion. Instagram commissioned a study to understand the usage pattern in India and found over 90 percent of its users in the country to be under 30 years of age. "Indians on Instagram are mostly young, mobile-first users with high spending power. They follow brands to keep in touch with the latest products, learn about deals and shop for products online and over 50 percent of Indian Instagrammers have frequently purchased products and services from the brands they follow," the study conducted by Nielsen said. Also, Indians use Instagram to express themselves artistically among like-minded people, follow celebrity trends as well as to discover and share food and travel options, it said. "These insights are useful as we get a better understanding of our audience. In September, we opened our platform to businesses of all sizes in India, helping advertisers drive results," she said. In India, advertisers on Instagram include P&G, Nestle, Paper Boat, Grofers, and TrulyMadly, among others.