We live at the most interconnected moment in human history. From India's rural hinterlands to the coastal metropolises of Africa, from American suburbs to East Asia's bustling, hi-tech cities, access to the Internet dictates daily rhythms and opens doors for new opportunities.

Yet, as a recent McKinsey report pointed out, the majority of the world's population -- about 60 percent -- is still offline. The report explores the main barriers to entry, which include poverty, digital illiteracy, and a dearth of infrastructure.

Access to the Internet, says the Brookings Institute, is a key indicator of one's economic prospects:

People without Internet access are more likely to be poor, live in rural areas, and uneducated. Fifty percent of these individuals live below the poverty line in their respective countries. Sixty-four percent of them live in rural areas. About 28 percent of the offline population is illiterate while nearly every person connected to the Internet can read and write.

Three-quarters of the world's offline population live in just 20 countries. More than a billion Indians have no internet access, despite the international image of their nation being so aligned with web-enabled outsourcing and the world's booming tech industries. Almost 1 in 5 Americans is also offline. If current trends hold, the world may add nearly a billion people to its online population by 2017, says Brookings.

But that will leave some 4.2 billion people still offline and very much in the dark of the 21st century.