A majority party is the political group in a legislative body with the most voting members. For example, if 47 of the 100 Senators in the U.S. Senate are Republicans and 53 are Democrats, the Democrats are the majority party.
If there are the same number of Democrats and Republicans in the United States Senate, the party to which the Vice President, who is the President of the Senate, belongs is considered the majority party in the Senate. In the House of Representatives, the very powerful position of Speaker of the House generally comes from the majority party in the House. The House Majority Leader is second in importance within the body. In many other countries, the majority party also plays an important role in the direction the government takes.