Impeachment is the legal process of bringing charges against a government official to determine whether he or she can be forcibly removed from office. Despite a common misconception, impeachment is not the removal from office itself, but rather a necessary step towards this removal in many of the world's governments. If the trial following impeachment results in the official's conviction, he or she will be removed from office. However, not every impeachment leads to a conviction.

Many countries include impeachment in their constitutions, though the particulars may differ. For example, who may be impeached, the body allowed to initiate impeachment proceedings, and the amount of votes required to convict the impeached official may vary. Usually, only a constitutional body has the right to initiate impeachment, and in most cases it is the legislative entity. Impeachment is typically used only in the case of crimes committed by the official in question, not for simple mismanagement or unpopularity. An impeachment trial is similar in format to any other type of trial.

In some countries, such as Ireland, only the President may be impeached. In many other countries, any public official is subject to impeachment for crimes committed. In the United States, impeachment may happen on both the federal and the state level. State impeachments are governed by individual state constitutions and initiated by state legislative bodies.

Impeachment is fairly rare in today's world. England, for example, has not used impeachment since 1806. Impeachment is considered an extreme measure, only to be used in cases of extreme misconduct on the part of the official. Often, the threat of impeachment is enough to make an impact, such as when US President Richard Nixon resigned from office in 1974 under the threat of impending impeachment.

While 17 federal officers have been impeached in the United States since the country was founded, only seven were removed from office as a direct result of the impeachment proceedings. Andrew Johnson and Bill Clinton are the only Presidents to have been impeached, in 1868 and 1998 respectively, though the Senate acquitted both men. Recently, there has been some support for the possible impeachment of President George W. Bush for various alleged crimes, including ignoring the Geneva Conventions and recording civilians' conversations without their knowledge or consent, but Congress has so far taken no official action towards impeachment.

Though impeachment is rare, many historians and political analysts argue that most cases are politically driven and even frivolous in retrospect. Nevertheless, impeachment remains a powerful tool to keep the conduct of elected officials above board, even if it is rarely exercised. The mere existence of an impeachment clause in a country's constitution can have an effect on the conduct of its leaders.