
Paper ballots are considered the gold standard of vote counting. Three states in the U.S. use them, Colorado, Oregon, and Washington. Other states claim to use them, but they are not reliable. Some just issue receipts repeating what the voter intended, but offering no guarantee that is what is recorded. Quite a few states offer nothing, just a smile and thank you to the voter, no assurance at all that the vote was even recorded, much less counted.
In the three states mentioned, voters hand-enter their choices on ballots, and the ballots are then run through optical scanners to tally the vote. It is not fool proof, as the scanning software can be corrupt, but the ballots are stored under lock and key for at least 22 months for recounts and perhaps study or statistical sampling. I think that 22 months storage is the law.
