Tens of millions of voters in the United States will go to the polling booths on Tuesday.

But the results of the election — including whether Kamala Harris or Donald Trump will become the next president — won’t be official until votes are counted and verified, which could take days to fully complete.

In the battleground states expected to determine the winner of the election, the process will be closely scrutinized. Trump is already questioning the reliability of many of their voting processes, and in 2020 he has challenged the results of many of their votes in court.

Here’s what you need to know about voting in 2024.

The first polling stations start to close at 6pm EST (11pm BST) on Tuesday, but vote counting will continue well after that.

In most cases, it could take weeks for an official count to occur, partly because of state rules.

For example, in two battleground states — Pennsylvania and Wisconsin — election workers are not allowed to start processing mail-in ballots until Election Day. It is expected that this will significantly delay the counting.

It is important to note that news organizations use unofficial results and projections when announcing winners on election night or the following days, rather than waiting for the final and official count.

Counting also varies from location to location and depends on the equipment used.

Some counties “feed” the ballots into optical scanners, while others may use touch screen systems or voting machines to record the votes.

The scanners are the most common. They tabulate the results, which are then manually totaled and double-checked by hand.

The results are in turn shared with election officials, the parties and ultimately the public.

Counting could be delayed by disruptions, legal challenges or complications surrounding provisional ballots.

Numerous legal challenges have already been filed.

As of Nov. 1, there were 203 voting and election lawsuits pending in 40 states, according to Marc Elias, a Democratic elections lawyer who filed many of the responses to Trump’s 2020 lawsuits.

They are concentrated in the battleground states of Georgia, which by his count have 25 legal challenges, Pennsylvania, North Carolina, Wisconsin and Arizona.

Provisional ballots are given to voters when it is unclear whether they are eligible to vote. This can happen, for example, if a person cannot be found in the registers of registered voters.

Ballots can also be challenged by election workers or — in some states — by poll workers. Once contested, ballots must be reviewed by election supervisors and made available to state commissions before being included or removed from the official final count.

Each state has its own procedure for recounts and what can trigger them.

In the battleground states of Pennsylvania and Michigan, recounts occur automatically when the number of votes each candidate has received is particularly close.

For example, in the case of Pennsylvania, an automatic recount is required if the margin of victory is less than or equal to half a percentage point.

Recounts can also be requested by candidates, courts or groups of voters, although the rules vary considerably from country to country.

Normally a request must be submitted within three to seven days.

In the vital swing state of Arizona, for example, a recount must be requested within two days of the announcement of the unofficial results.

Once again, the results the public will hear on election night are not official — and are instead a mix of preliminary data released by officials and projections from the Associated Press or Reuters news agencies.

All states must certify their official results by December 11.

But many key states have earlier deadlines. For example, Georgia must release its final count by November 22, while Michigan and Pennsylvania have until November 25.

The next step takes place six days later, on December 17, when presidential “electors” meet and send their states’ results to Congress.

The electoral votes must be received by the president of the Senate – the vice president, in this case Kamala Harris – no later than December 25.

State electors came under intense scrutiny in 2020, as Trump and officials in seven states tried to use alternative or “fake” electors to overturn his election loss.

Some expect the certification process to be dragged out by legal battles this year, including potentially numerous challenges from Trump and his political allies in Pennsylvania.