A prime minister is the head of government in many countries, responsible for running the country's day-to-day operations and leading its government. Unlike a president, who is often both head of state and head of government, a prime minister typically works alongside a monarch (like a king or queen) or a president who serves as head of state.

In countries like the United Kingdom, Canada, Australia, and Japan, the prime minister holds the main political power. They choose cabinet ministers, propose laws, manage the budget, and help make major decisions about how the country operates. The prime minister usually comes from the political party that won the most seats in parliament, and parliament can remove them through a vote of no confidence if they lose support.

Think of it this way: in a country with a prime minister and a monarch, the monarch is like the school principal who represents the whole school and attends ceremonies, while the prime minister is like the principal’s top manager who runs things day to day, organizing schedules, leading staff, and solving problems.