What does it mean for a political party to "be in power"?

Ordinarily, after an election, the leader of the political party with the most seats in the House of Commons is invited by the Governor General to form the government. After being appointed by the Governor General, the leader of this party becomes the Prime Minister. If the party in power holds at least half of the seats in the House of Commons, this is called a majority government. If the party in power holds less than half of the seats in the House of Commons, this is called a minority government.

The Prime Minister and the party in power run the government as long as they have the support or confidence of the majority of the MPs. When the House of Commons votes on a major issue such as the budget, this is considered a matter of confidence. If a majority of the members of the House of Commons vote against a major government decision, the party in power is defeated, which usually results in the Prime Minister asking the Governor General, on behalf of the Sovereign, to call an election.

The Prime Minister chooses the ministers of the Crown, most of them from among members of the House of Commons. Cabinet ministers are responsible for running the federal government departments. The Prime Minister and the Cabinet ministers are called the Cabinet and they make important decisions about how the country is governed. They prepare the budget and propose most new laws. Their decisions can be questioned by all members of the House of Commons.

The other parties that are not in power are known as opposition parties. The opposition party with the most members of the House of Commons is the Official Opposition or Her Majesty’s Loyal Opposition. The role of opposition parties is to peacefully oppose or try to improve government proposals. There are three major political parties currently represented in the House of Commons: the Conservative Party, the New Democratic Party, and the Liberal Party.