It is Commonwealth Day on Monday, an annual celebration observed by people across the Commonwealth, in Africa, Asia, the Caribbean and Americas, the Pacific and Europe.

Falling every year on the second Monday in March, this year’s event will be marked with a service attended by King Charles for the first time, who will be joined by the rest of the royal family at Westminster Abbey.

The aim of Commonwealth Day is to honour the history and shared values of Commonwealth states and it is a public holiday in some Commonwealth countries.

What is the Commonwealth?

The Commonwealth of Nations, generally known as the Commonwealth, is a political association of 54 member states, almost all of which are former colonies of the British Empire.

Formed in 1949, it now includes about 2.6 billion people and makes up a quarter of the world’s land mass.

Member countries have no legal obligations to one another but are connected through their use of the English language and historical ties as former colonies. Their stated shared values of democracy, human rights and the rule of law are enshrined in the Commonwealth Charter and promoted by the Commonwealth Games, which take place every four years.

Queen Elizabeth was the longest reigning head of the Commonwealth, with King Charles automatically taking the position after her passing.

Why was the Commonwealth formed?

The Commonwealth has its roots in the British Empire.

Over time, different countries within the British Empire gained varying levels of freedom from Britain. Semi-independent countries were called dominions. Leaders of the dominions attended conferences with Britain from 1887.

In 1926, the Imperial Conference was held, with leaders of Australia, Canada, India, the Irish Free State, Newfoundland, New Zealand and South Africa attending. At the conference, Britain and these dominions agreed that they were all equal members of a community within the British Empire. This community was called the British Commonwealth of Nations.

As more and more countries gained independence from the British Empire, at the Commonwealth Prime Ministers Conference in London in 1949, it was decided that republics and other countries could be part of the Commonwealth. Thus, the London Declaration created the modern Commonwealth of Nations.

Since 1949, independent countries from Africa, the Americas, Asia, Europe and the Pacific have joined.

What is the history behind Commonwealth Day?

Originally known as Empire Day, Commonwealth Day was established in 1902 to honour Queen Victoria the year after she died.

However, the idea of a day that would “remind children that they formed part of the British Empire” was conceived in Canada in 1897.

Empire Day actually wasn’t officially recognised until 1916, having been celebrated unofficially in Canada for 14 years. It took another 10 years for its popularity to really grow – in 1925, an Empire Day Thanksgiving celebration at Wembley Stadium drew around 90,000 in attendance.

In 1958, Harold Macmillan, then the prime minister, rebranded Empire Day as Commonwealth Day.

What will happen on Commonwealth Day this year?

This year’s Commonwealth Day theme is “Forging a sustainable and peaceful common future”.

According to the website, the theme combines the active commitment of member states to support the promotion of peace, prosperity and sustainability, especially through climate action, to secure a better future for young people and improve the lives of all Commonwealth citizens.

In London, the day will be celebrated with a multicultural and multi-faith service held at Westminster Abbey.

The service will feature a procession of young flagbearers representing each of the 56 nations of the Commonwealth, as well as a wreath-laying ceremony at the Commonwealth Memorial Gates and a flag-raising event for the Commonwealth Flag for Peace.

There will also be a number of activities including civic gatherings, debates, school assemblies, flag-raising ceremonies and a host of cultural events celebrating Commonwealth peoples.