As head of state, she welcomes them to the UK and meets them when touring around the world.
From rulers, including UAE Founding Father, the late Sheikh Zayed bin Sultan Al Nahyan, and Jordan’s King Abdullah II, to presidents and prime ministers, she has been there to receive them.
The queen has met leaders of the UK’s closest allies and some of its critics. Sometimes a world leader is honoured with a state dinner, often it is a handshake and a chat but, for the UK, she is a vital cog in its soft power diplomacy.
The queen is the head of state of the UK and 14 other countries — Antigua and Barbuda, Australia, the Bahamas, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, Solomon Islands, St Kitts and Nevis, St Lucia, St Vincent and the Grenadines, and Tuvalu.
As she approached the platinum jubilee, Barbados removed the queen as its head of state.
In June, the queen will celebrate her platinum jubilee with a four-day public holiday that includes a special Trooping the Colour birthday parade.