It’s no secret that India has a massive internet user base.

The number of internet users is expected to hit 500 million by 2017, driven by the growing use of mobile devices. That would make the country second in the world after China.

But many of these users are increasingly surfing the web using regional languages, not English. According to a report by the Internet and Mobile Association of India (IAMAI) and research firm IMRB International, the country’s local language internet user base jumped 47% to 127 million in June 2015, compared to a year ago.

In the same period, the number of local language users in urban areas rose 51% to 81 million. In rural areas, the number was 46 million.

Nearly 88% of Indians converse only in regional languages, according to the IAMAI, with Hindi being the most widely used. Census data from 2001 show that over 422 million Indians listed Hindi as their mother tongue, accounting for about 41% of the population. The other most common languages were Bengali, Telugu, Marathi and Tamil, whose speakers constituted about 30% of the population.

This means there’s a lot more room for growth in local language content. According to the IAMAI, boosting regional language content could increase India’s internet user base by 39%, with 75% of the growth coming from rural areas and 16% from the urban segment.

While popular websites in India such as Google and Facebook do offer regional language versions, local language content still lags far behind English options. According to W3Techs, a site that provides information on how technology is used on the web, 55% of all global websites are in English, with Hindi, Bengali and Tamil websites each accounting for less than 0.1% of the total.

The big problem is that many websites and apps that do offer regional language content only do so partially and some even suffer from seriously awkward translations. For instance, according to the IAMAI, in the phrase ‘Camera 16MP’, the ‘MP’ is often translated to saansad in Hindi, meaning member of parliament.

Moreover, online advertising in India mostly relies on English, with only 5% of digital ad spends dedicated to local languages.

But with smartphones bringing even the smallest Indian towns online, it’s time to invest in local language content to expand India’s internet user base even further.