A presidential system is a form of government where the president serves as both the head of state and the head of government. In this system, the president is elected separately from the legislative body, allowing for a clear separation of powers. This structure is designed to prevent any one branch of government from becoming too powerful. In a presidential system, the president has significant authority, including the ability to veto legislation and appoint government officials. Countries like the United States and Brazil utilize this system, which often leads to a stable executive branch, but can also result in conflicts between the president and the legislature.