EVMs and VVPAT Explained: How India Votes

Every vote in a UP Assembly election is cast on an Electronic Voting Machine, or EVM — a system India has used for every national and state election since 2004, after a series of smaller pilots through the 1980s and 1990s. It is one of the largest deployments of purpose-built voting hardware anywhere in the world, and also one of the most scrutinised, debated and, at times, misunderstood pieces of election infrastructure in the country, precisely because it sits at the exact point where public trust in the entire electoral process either holds or breaks down.

Here is what the machine actually is, how a vote gets from your fingertip to the final count, and what the paper trail added more recently changes about how that process can be independently verified.

What an EVM Actually Is

An Indian EVM is not a single device but two connected units. The Ballot Unit sits with the voter inside the voting compartment and lists every contesting candidate’s name and party symbol next to a blue button. The Control Unit, kept with a polling officer at the front of the booth, is what actually registers and stores each vote once the officer activates the ballot for that voter. The two are connected by a cable, and only one vote can be registered per activation, which is itself one of the basic safeguards against repeat voting at a single booth.

Crucially, the machines are standalone. They run on a 7.5-volt battery rather than mains power, and they are never connected to the internet, to any wireless network, or to each other, at any point before, during or after polling. That is a deliberate design choice, not an oversight — it removes remote hacking, in the sense most people picture when they hear about voting-machine security, as an available attack surface entirely, since there is no network connection through which a remote attacker could reach the device in the first place.

Who Builds Them

EVMs used in Indian elections are manufactured exclusively by two Indian public-sector undertakings — Bharat Electronics Limited and Electronics Corporation of India Limited — under specifications set by the Election Commission. Early technical design work involved professors from IIT Bombay, brought in specifically to help design a machine robust enough for deployment across hundreds of thousands of polling stations in wildly varying conditions, from dense urban booths to remote rural ones with unreliable power. No private company, and no foreign vendor, is involved in manufacturing the machines actually used at Indian polling stations.

What Counting Day Actually Looks Like

On counting day, sealed Control Units from every polling station in a constituency are brought to a central counting location under security escort, where party-appointed counting agents are present to observe the process directly. Each Control Unit’s stored vote totals are displayed and recorded in front of these observers round by round, with results for larger constituencies typically announced in successive rounds as more machines are processed, rather than as a single instantaneous total — which is why constituency-level results are often reported as evolving over several hours on counting day rather than appearing all at once.

VVPAT: The Paper Trail

Since being phased in nationally after a 2013 Supreme Court directive, every EVM used in an Indian election is paired with a Voter-Verified Paper Audit Trail printer, universally referred to as VVPAT. After you press the button for your chosen candidate on the Ballot Unit, the VVPAT machine prints a small slip showing that candidate’s name, serial number and party symbol, and displays it behind a small glass window for roughly seven seconds so you can visually confirm, in that moment, that your vote was recorded for the candidate you actually intended.

After that seven-second display window, the slip drops automatically into a sealed box inside the VVPAT unit, where it is preserved for potential later verification. You never handle the slip yourself, and no one else in the room sees which candidate it names — the display window is angled and sized specifically so that only the voter standing directly in front of it can read it.

Mock Polls and Pre-Election Testing

Before polling begins each day, every machine goes through a mock poll in front of party candidates or their authorised agents — a small number of test votes are cast for each candidate, tallied, and matched against the expected result before the machine is formally sealed and switched to live polling mode. This gives every contesting party’s own representatives, not just Commission staff, direct sight of each machine functioning correctly immediately before it is used, rather than asking voters to simply trust the equipment on faith.

How the Paper Trail Is Actually Verified

The Election Commission mandates that VVPAT slips from a randomly selected sample of polling stations in every single constituency be counted by hand and cross-checked against the electronic tally from the Control Unit — a safeguard strengthened in 2019, following public and legal pressure, from a smaller sample size to the current 2% of polling stations per constituency, selected by lottery after polling closes so no one can know in advance which booths will be audited.

If a mismatch turns up between the paper count and the electronic count at any audited booth, it triggers a full manual recount of the VVPAT paper slips for that specific polling station, with the hand-counted paper result treated as authoritative over the electronic tally in that scenario. Indian courts, including the Supreme Court, have reviewed legal challenges to the EVM-VVPAT system on multiple occasions and have consistently upheld it as constitutionally valid, while also being the body that pushed the Commission to expand the VVPAT sample size in the first place.

What Happens to a Malfunctioning Machine

EVMs do occasionally malfunction on polling day, just as any piece of hardware deployed at this scale eventually will — a battery failure, a jammed VVPAT printer, or a display fault are the most common issues reported. When this happens, the affected machine is replaced with a reserve unit kept on standby at every polling station, and voting resumes once the replacement is in place. Votes already cast on the faulty machine before the malfunction remain valid and are counted normally; the replacement only affects votes cast after the swap.

Common Concerns, Addressed Directly

Two concerns come up repeatedly in public discussion of EVMs and are worth addressing directly. The first is tampering during manufacturing or storage, before an election even begins — the Commission addresses this through a multi-stage checking process involving engineers from the manufacturers themselves, randomised machine allocation to constituencies shortly before polling so no one can predict in advance which specific machine will be used where, and sealed storage with round-the-clock security between elections.

The second is the possibility of a software-level manipulation embedded at the chip level during manufacturing. This is the concern most directly addressed by the VVPAT system covered above — because the paper trail is generated independently of the electronic tally and physically verified against it in a randomised sample of booths every single election, any systematic discrepancy between the two would be expected to surface in that audit process, which is precisely the safeguard the Supreme Court pushed the Commission to strengthen in 2019.

Further Reading

For the full technical and legal history — including the original 1982 Kerala pilot, the gradual legal amendments through the late 1980s that permitted EVM use, the 1998 expanded trial, the 2004 national rollout, and the subsequent security analyses and court cases — see the Electronic voting in India ↗ entry on Wikipedia, which documents the full timeline in more depth than fits here.

To understand how the votes an EVM records ultimately translate into an actual election result and, eventually, a government, read our broader guide to how UP Assembly elections work, or see the wider machinery of oversight around the whole process in our piece on the Election Commission’s role.