President Trump has repeatedly attacked voting by mail as a less secure method than absentee voting, claiming without evidence that it will lead to rampant fraud and creating confusion about whether there is a difference between those practices.

The bottom line: Some states prefer one term over the other, but both “absentee voting” and “mail-in voting” refer to the method of using the mail to deliver ballots to voters. Regardless of the term used in your state, all ballots delivered to voters by mail are verified before they are counted.

Now, let’s dig in.

Absentee ballots and mail-in ballots

The term “absentee ballot” has been historically used to describe a ballot that is sent to a voter outside of a polling place. When the use of such ballots began, the idea was that only voters who were “absent” from their local voting jurisdiction on Election Day would be able to request and cast their ballot through the mail.

Absentee voting started during the Civil War, allowing soldiers to cast their ballots in their home states. Over time, more states began expanding the use of absentee ballots to make voting more accessible to more people, including those who have a disability, are facing emergency situations such hospitalization, are being sequestered on a jury or are even on a spaceflight.

Absentee voting has become so common that in 34 states and the District, any voter can ask for an absentee ballot, even if the voter is physically able to vote in person on Election Day, a practice called “no-excuse absentee voting.” That includes Florida, where Trump is registered to vote and cast an absentee ballot in this year’s primary.

Some states that still require specific excuses to vote absentee have temporarily relaxed their rules this year because of the coronavirus pandemic, allowing voters to cite fear of the virus as a valid excuse.

As the use of absentee voting evolved, election officials began referring to the practice with other terms, such as “advanced ballots,” “mailed ballots,” “vote-by-mail ballots” and “mail ballots,” according to the National Conference of State Legislatures (NCSL).

Some states prefer to call it “mail-in voting” rather than “absentee voting,” because voters will be mailed a ballot regardless of whether they are in town or “absent” from their polling precinct on Election Day.

Why are there so many terms? It’s a result of a decentralized election administration system in the United States, in which each state sets its own rules on how to conduct elections, experts say. And each state’s rules and regulations around absentee voting vary.

“This issue highlights the fact that we have a diversity of approaches to election administration in the United States. Some people have called it voting at home, some people have referred to it as voting outside of the polling place,” said Michael Thorning, associate director of governance at the Bipartisan Policy Center. “But at the end of the day, these are systems for delivering ballots to voters.”

Even though these ballots are mailed to voters, voters can choose to return them in person. Depending on the state, a voter who receives an absentee ballot in the mail can return it by putting it in a mailbox, dropping it in a secure ballot drop-off box or dropping it off at their local elections office.

Or, in some states, you can change your mind and show up at the polls on Election Day to vote in person, and your mailed ballot will be voided when you cast a new ballot there.

Because of the confusion around the terms, the NCSL is now using the term “absentee/mailed ballots” to refer to ballots that are mailed to voters by election officials.

So what is universal mail voting? Is that less secure?

Trump’s rhetoric about mail voting appears to have persuaded many Republican voters that the practice is risky, stirring fears among GOP strategists that they could fall behind in a method that is key to getting out the vote. More recently, the president has stressed the safety of “absentee voting,” arguing that it is “universal mail voting” instead that could corrupt the election.

“Absentee ballots, by the way, are fine,” Trump told reporters in August. “But the universal mail-ins that are just sent all over the place, where people can grab them and grab stacks of them, and sign them and do whatever you want, that’s the thing we’re against.”

Trump is referring to a practice in which election officials proactively send voters mail ballots. Currently, five states hold their elections entirely by mail: Colorado, Hawaii, Oregon, Washington and Utah. This means all eligible voters automatically receive a ballot in the mail, regardless of whether they request it. They can choose to mail it back or drop it off at a designated location, depending on the rules of each election and state.

Three other states (California, Nebraska and North Dakota) allow counties to decide whether to conduct an election entirely by mail, and at least 17 states allow certain elections to be held entirely by mail, according to the NCSL.

States that have been conducting all-mail elections for years have rigorous processes in place to verify and track ballots. Voters must follow specific directions to return the ballot that they received in the mail, such as signing an affidavit. Election officials compare the signature on the ballot envelope with the signature they have on file to make sure they match. Many states also have unique bar codes on each ballot that tie them to a specific voter.

A Washington Post analysis of data from three states that conduct universal mail elections found a minuscule rate of potentially fraudulent ballots, undercutting the president’s claims.

After the coronavirus outbreak, some states decided to send ballots to all voters this year to reduce the risk of infection. That includes California, Nevada, Vermont and New Jersey, as well as the District.

All mail ballots are verified before they are counted, regardless of whether they are cast in an all-mail state, said Wendy Underhill, direction of elections and redistricting at the NCSL.

Still, Republicans have seized on accounts of some unattended ballots found at apartment buildings in Las Vegas and Paterson, N.J., during this year’s primaries, saying that states that do not have experience with all-mail elections should not be trying to conduct them this year. Election experts say that the mailing of ballots to all voters should be accompanied by rigorous efforts to make sure that voting rolls are accurate and up to date.

In announcing New Jersey’s decision to send ballots to registered voters in the fall, Gov. Phil Murphy (D) said last week that the primary “gave us the opportunity to see what worked and where we could make improvements.”

Okay, but I keep hearing that mail-in ballots are less secure. What are election officials doing to make sure there’s no funny business?

They’re doing a lot. There are strict security measures in place for all ballots cast by mail, and election officials take rigorous steps to make sure the voting method is checked and double-checked so they are being filled out by the appropriate, eligible and registered voter.

Each state’s process differs. But generally, election officials check the voter registration and other information to confirm that mail ballots are sent only to voters who are eligible to cast that ballot. In about half the states, election officials can match a specific ballot to a specific voter using technology, using tracking bar codes or tally marks that are unique to each voter.

A ballot is counted only after election officials have conducted a thorough check to make sure that it was filled out by the voter to whom the ballot was sent. About 15 states require signatures on the ballots to be matched against the signatures on their voter registration. Ballots are rejected if they are not sent back in the envelope that the state provided the voter. (Check out our explainer on how to prevent your mail ballot from being rejected.)

Several states have ballot-tracking services that allow voters to check the status of their mailed ballot online or via text updates, making tracking as convenient as a package delivery through shipping services.

Election officials know the exact number of ballots sent out by mail and cast by voters. So it would almost certainly raise red flags among local election offices if there were any effort to print counterfeit ballots or to send fake ballots by mail, according to election officials.