The results for the United States (US) midterm elections are mostly in and show that the Republican Party will remain in control of the Senate while the Democratic Party now holds a majority in the House of Representatives. What does this mean for President Donald Trump's administration? Here is a dummies guide to the midterm election results.Who won the elections?The Democrats have taken control of the House of Representative while the Republicans strengthened their hold on the Senate. With almost all the races called, Democrats have increased their seats in the House while Republicans have taken three seats from the Democrats in the Senate.Why does it matter that the Democrats won the House of Representatives?With the Democrats controlling the House, they are able to hinder Trump's ability to implement programs as he wishes. The party with a majority in the chamber controls its committee chairmanships and has the power to issue subpoenas – so a Democrat-controlled House could enforce aggressive oversight of investigations of the president's administration, including alleged Russia collusion, Trump's business dealings and sexual assault allegations against him, using their power to order witnesses to testify.The House can also initiate impeachment proceedings against the president, although it would need a two-thirds majority in the Senate to remove him from office.Nancy Pelosi, the woman expected to become the new Democrat Speaker of the House, said in a speech that Wednesday would be a "new day in America", adding: "We've all had enough of division."However, if the Democrats overplay their hand, Trump will be able to make the situation work in his favour by pinning blame on them for congressional gridlock when legislation stalls.What does a Republican Senate mean?With the Republicans retaining control over the Senate, they will continue to approve Trump's cabinet nominees and appoint conservative judges to US courtrooms.What do the results say about support for Trump?With Republicans unseating a string of Democratic senators up for re-election in states Trump won in 2016, it is an indication that many of the president's supporters are still backing him two years into office. While his approvement ratings are relatively low, the fact that unemployment is at an all time low and the US economy is growing has given the Republican Party a major boost.Although Trump was not on the ballot, he loomed large throughout the election — the way presidents historically have in midterm elections — and many voters seized the opportunity to make their feelings known.About two-thirds of those interviewed in exit polling said Trump was a big factor in their vote, with 40% of those saying they cast their ballots in opposition to the president and 25% expressing support.What are the midterm elections?Americans vote for a new president every four years in a general election. Midterm elections occur halfway through a president's term and are usually held in November. Midterm elections are not the same as state and local elections, which are held yearly.What do Americans vote for in the midterms?Americans vote for members of the Senate and the House of Representatives, which make up the upper and lower chambers of Congress. Congress is the legislative (i.e. law-making) branch of the US federal government.The House of Representatives consists of 435 seats that are up for election every two years. One third (35) of seats in the Senate is also up for election as members of the Senate serve staggered six-year terms. Also up for grabs this year were 36 state governors' offices, three US territory governors' offices, many mayors' offices and local officials. Voters also decided on ballot measures such as former felons' right to vote.How does the Senate election work?The Senate is composed of senators, each of whom represents a single state in its entirety, with each state being equally represented by two senators. The winners in each state are the candidates who receive a plurality of the popular vote. To win the Senate, a party needs to win 51 seats. The Republicans previously held 51 seats and the Democrats 49. However, out of the 35 seats up for election in 2018, 26 were held by Democrats. The party therefore needed to keep all 26 their seats and gain two seats to take control of the Senate – a tall order. How does the House of Representatives election work?To win the House, a party needs to win 218 of the 435 seats. Before the election the House had 236 Republicans and 193 Democrats, with six vacant seats. The Democrats therefore need a net gain of 24 seats to win a majority.The House is composed of representatives who sit in congressional districts that are allocated to each of the 50 states on a basis of population as measured by the US Census, with each district entitled to one representative. All representatives are directly elected.The Republican Party previously controlled both the House and the Senate.Do people actually vote in the midterms?Voter turnout in the midterms is usually much lower than in the general elections, but this year seems to be a record year. Three days before the election, the New York Times reported that 31.5 million people had already voted in the absentee elections. According to the Pew Research Institute the number of votes cast in Democratic primaries for the House were 84% higher in July than at the same point in the 2014 midterm primaries.What else?This year's midterms are said to be the most expensive in the history of the US with a total of $5.2bn being spent on campaigning, according to the Center for Responsive Politics.