A state visit is a formal visit by a head of state to a foreign country, at the invitation of the head of state of that foreign country, with the latter also acting as the official host for the duration of the state visit. Speaking for the host, it is generally called a state reception. State visits are considered to be the highest expression of friendly bilateral relations between two sovereign states, and are in general characterised by an emphasis on official public ceremonies.

Less formal visits than a state visit to another country with a lesser emphasis on ceremonial events, by either a head of state or a head of government, can be classified (in descending order of magnitude) as either an official visit, an official working visit, a working visit, a guest-of-government visit, or a private visit.

In parliamentary democracies, while heads of state in such systems of government may formally issue and accept invitations, they do so on the advice of their heads of government, who usually decide on when the invitation is to be issued or accepted in advance.

Queen Elizabeth II was the most travelled head of state in world history, having made 261 official overseas visits and 96 state visits to 116 countries by the time of her Diamond Jubilee in 2012. Although she was sovereign of each of the Commonwealth realms, in practice, she usually performed full state visits as Queen of the United Kingdom, while the relevant governor-general undertook state visits for his or her respective country on the sovereign's behalf. However, the Queen occasionally made some state and official visits representing one of her other Commonwealth realms.