The symbol-oriented design also makes voting more widely accessible in a country with 287 million illiterate adults—nearly 37 percent of the worldwide total—and a multilingual electorate that speaks 22 officially-recognized languages and hundreds more unofficial ones. But perhaps the EVM's most impressive feature is its price tag: each unit costs only 10,500 Indian rupees, or about $175. By comparison, even older, used voting machines in the U.S. can cost around $6,000.

After a decade of sporadic and unsanctioned use of EVMs, India legalized the devices in 1988 alongside the existing (and often-maligned) paper-ballot system. They became standard features of elections in 1998 and the sole method for casting votes in the 2004 general election, in which almost 1.1 million EVMs were deployed in polling stations across the country. The Indian government boasts that "EVM has become the leitmotif of the world's largest democratic exercise and gets smarter with each avatar." Official election materials cite the EVM's superiority over paper balloting by noting the reduction in environmental waste, the speediness of tabulating results, and the decrease in spoiled or improperly cast votes. Another strength, according to election officials, is the EVM's role in combating electoral fraud through "booth capturing"—an ugly tactic where a candidate's supporters storm a polling place, sideline legitimate voters, and cast ballots—and ballot-stuffing.

But the machines have their limitations as well. EVMs can only record a maximum of 3,840 votes each (the Election Commission says each polling place should only serve about 1,500 voters) and can only list a maximum of 64 candidates at a time to vote for. Because India's elections are staggered over a six-week period, votes are tabulated in one region and the machines are then reused in another. In March, the Election Commission estimated it would have 1.7 million ballot units and 1.8 million control units—some polling places have more than one ballot unit per control unit—for this year's election. Each Indian constituency is required to keep 10 percent more EVMs than necessary for emergency situations.

Like all electronic voting systems, EVMs also invite concerns about outside tampering. Since implementing the devices nationwide, the Election Commission has insisted that the machines are not susceptible to hacking or other forms of fraud. But a 2010 report by Indian computer-security experts challenged this claim after examining one of the machines and cited numerous vulnerabilities, especially if a malicious user had access to the EVMs in advance. "The technology’s promise was that attacks on the ballot box and dishonesty in the counting process would be more difﬁcult," the report concluded. "Yet we ﬁnd that such attacks remain possible, while being potentially more difﬁcult to detect."