Deportation is the process of legally removing any foreign national from the borders of the United States. Individuals may voluntarily leave the country rather than being forcefully deported, or they can be detained, brought before an immigration court, and deported by force. 

There are a number of reasons why an individual could be deported. If an immigrant is undocumented, violates their visa terms, commits a criminal act, or poses a public danger to the country, they will be deported. Sometimes there will be a deportation hearing which will allow the immigrant to defend themselves in front of a judge and explain why they shouldn’t get deported. However, some violations will result in immediate deportation without any court proceedings at all. 

In most cases, a U.S. citizen cannot be deported. Since deportation is the removal of a foreign national from the United States, being a naturalized citizen makes an individual ineligible to be deported. In some extreme cases, the U.S. government can undergo a process to denaturalize an individual. This is incredibly rare and only occurs when the individual fraudulently applied for naturalization or otherwise committed an extreme offense against the U.S. government. If an individual is denaturalized, then they can be deported.