The Queen's Speech, which formally opens Britain's parliament each year, is a colorful ceremony steeped in traditions dating back centuries. The costumes and elaborate rituals may appear eccentric today, but many reflect historic tensions between the monarchy and Parliament.

Here's a look at the pageantry and customs of the event and what they mean:

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SECURITY 'PRECAUTIONS'

Before the queen travels to Parliament from Buckingham Palace, royal bodyguards known as Yeomen of the Guard perform a ceremonial search of the cellars of the Palace of Westminster. The tradition, which dates from the 1605 "gunpowder plot" to blow up Parliament, is followed by a police sweep.

Another quirky tradition is the "hostage" lawmaker — a government whip is "kidnapped" to be held at Buckingham Palace to ensure the monarch's safe return after she delivers her speech. The custom dates centuries back to a time when the monarch and Parliament were on less cordial terms.

The queen delivers her speech from the House of Lords — no monarch has set foot in the Commons since Charles I tried to arrest five lawmakers for treason in 1642.

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THE REGALIA

While the queen and her husband, Prince Philip, travel to Westminster in a state coach, the traditional items symbolizing the authority of the monarch — the Imperial State Crown, the Cap of Maintenance and Sword of State — travel in their own carriage ahead of the queen.

As the queen arrives at the House of Lords, greeted by a 41-gun salute, she walks up a set of stairs to the Robing Chamber, passing between cavalry soldiers in full dress with drawn swords. They are the only troops to bear arms within the palace.

The queen puts on the crown and the parliamentary robe in the room before emerging for the ceremony in the House of Lords. The sword and the cap are carried in front of her.

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THE BLACK ROD

Once the queen takes the gilded throne, an official known as the Gentleman Usher of the Black Rod — or simply Black Rod — acts as her messenger and summons the lawmakers gathered in the House of Commons. As he approaches the chamber, the door is slammed in his face, a symbol of the Commons' independence from the monarchy as well as its supremacy over the Lords.

Black Rod has to knock three times with his ebony staff at the door, which has a visible dent from all the knocking over the years, before he is allowed to enter.