Handwritten signatures are an outdated way of verifying votes, says VoteAmerica, a political NGO. Thousands of Nevada voters still need to verify mail-in ballots.

Faulty signatures come down to various factors, including voters not knowing how to sign their name, not updating their voter registrations in time and inconsistent signatures over time.

People's signatures can change throughout the course of their lives, typically with little consequence. But it's caused a larger issue for the U.S. election results in Nevada, where nearly 13,000 mail-in ballots are still being held,

More than 13,000 mail-in ballots were not counted across Nevada as of Friday due to signature issues, data from the state secretary of state's office said.