Tens of millions of voters will enter voting booths across the United States on Tuesday.

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

The process will be closely scrutinized in the battleground states that are expected to decide the election winner. Trump is already questioning the trustworthiness of many of their voting processes and in 2020 challenged the results of many of their votes in court.

Here's what you should know about voting in 2024.

The first polling stations will close at 6:00 p.m. EST (11:00 p.m. BST) on Tuesday, but the counting of votes will continue well beyond that.

In most cases, it can take weeks to receive an official tally, partly due to government regulations.

For example, poll workers in two battleground states – Pennsylvania and Wisconsin – are not allowed to begin processing mailed-in ballots until Election Day. This is expected to significantly slow down the count.

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

The count also varies from place to place and depends on the equipment used.

Some counties “feed” ballots into optical scanners, while others may use touchscreen systems or ballot marking devices to record votes.

The scanners are the most common. They present the results in a table, which are then manually counted and checked again by hand.

The results are in turn communicated to election officials, parties and ultimately the public.

Counting may be slowed by glitches, legal challenges or complications related to provisional ballots.

Numerous lawsuits have already been filed.

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

By his count, they are concentrated in the battleground states of Georgia, where there are 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 may be the case, for example, if a person cannot be found on the electoral rolls.

Ballots can also be challenged by poll workers or, in some states, poll watchers. Once challenged, ballots must be reviewed by election administrators and provided to state election boards before being included in the official final count or discarded.

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

In the battleground states of Pennsylvania and Michigan, recounts automatically occur if the vote totals of the individual candidates are particularly close to one another.

In the case of Pennsylvania, for example, 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 significantly between states.

Typically, an application 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 unofficial results being announced.

Again, the results the public hears on election night are not official – but a mix of preliminary data released by officials and forecasts from the Associated Press or Reuters.

All states must certify their official results by December 11th.

But many key states have earlier deadlines. Georgia, for example, must certify its final tally by November 22nd, while Michigan and Pennsylvania have until November 25th.

The next step comes six days later, on December 17, when the president's “electors” meet and submit the results of their states to Congress.

The electoral votes must be received by the President of the Senate – the Vice President, in this case Kamala Harris – by December 25th.

State voters were under intense scrutiny in 2020 as Trump and officials in seven states sought to use alternative or “fake” voters to overturn his election loss.

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