Commonwealth Day is being marked with an annual observance at Westminster Abbey in London. The BBC News website looks at the role of the organisation and hears the views of some readers.
In Diamond Jubilee year, the Queen celebrates 60 years as head of the Commonwealth.
The Commonwealth of Nations has been described by critics as merely a talking shop, raising questions about its effectiveness.
But with 54 members and counting, it seems the Commonwealth still has global resonance.
African countries such as Algeria, Madagascar and Sudan - as well as Yemen in the Middle East - have all applied to become members of the Commonwealth.
So why is membership considered by some to be such an attractive prospect?
The Commonwealth grants small countries greater access to network, and to raise matters of concern with their more influential fellow members.
As news website reader Mohammed al-Sharif from Sanaa says: "Yemen needs a lot of help. We have been through a civil war and we have economic problems.
"We have so many hopes that our president will lead us to a better future. But we cannot do anything without outside help."
In 2009, Rwanda became the latest country to join the Commonwealth.
Despite its brutal recent history, it was admitted into the Commonwealth because of its work towards democracy and the fact that the neighbouring countries of Uganda and Tanzania are members.
Josh from Kigali in Rwanda says: "It is beneficial to join different blocs because it widens opportunities, and encourages cultural exchange and trade."
The Secretary-General of the Commonwealth, Kamalesh Sharma, says it has played a major role in imparting its values of good governance, democracy and development around the world.
"The fact that there is a lot of interest in the Commonwealth indicates that it really is the club of the 21st Century.
"There is something that the Commonwealth has been doing right.
"The Arab Spring was all about the hope that the whole region could live by the values the Commonwealth has been espousing for so long."
He adds that the principles instilled by the Commonwealth in its members have been recognised by observers.
"The Ibrahim Index of good governance in Africa is a very reputable one. The last ranking showed that out of 54 countries in Africa, in the first eight, seven were from the Commonwealth," says Mr Sharma.
"This cannot be by accident. It is because of the Commonwealth's values that it becomes possible that institutions run better, elections are more credible and leaders are more conscious in their duties of leadership."
As the Commonwealth is a voluntary association with no formal constitutional framework, members work in the understanding that they fully commit to its values.
But the association's voluntary aspect, along with the fact that it cannot impose sanctions for non-compliance like other international blocs such as the UN and EU, have led to criticisms that it lacks bite.
The director of the Institute of Commonwealth Studies, Prof Philip Murphy, said the Commonwealth was very important to small states, but questioned the means to impose its values on members.
"It tries to preserve good government, rule of law and democracy for unstable states and acts in everyone's interests. But whether it has the resources to hold states to Commonwealth values is a different matter," he said.
The Commonwealth does help nations within its family as well as states that have chosen to go it alone.
One former member of the Commonwealth is Zimbabwe, suspended in 2002 over human rights abuses.
But after the suspension was extended because of continuing violations, President Robert Mugabe withdrew Zimbabwe from the Commonwealth altogether in the following year.
Despite this, the Commonwealth still works with organisations in Zimbabwe, and hopes that Zimbabwe will once again be a Commonwealth member.
"The Southern Africa Development Community is an interlocutor with Zimbabwe, and is trying to create the conditions where the next elections can take place in a secure and credible way," says Mr Sharma.
The Commonwealth is also involved in resolving the recent crisis in the Maldives after unrest led to the country's first democratically elected leader, President Mohamed Nasheed, stepping down.
The former Secretary-General, Sir Donald McKinnon, has been appointed as the Commonwealth's Special Envoy to the Maldives.
Sir Donald was secretary-general in 2000-08, at a time when democracy in the Maldives was in its infancy.
He has been tasked to talk to the political leaders in the country to help reach an agreement to restore democracy and ensure elections.
The Queen's role
Throughout her reign, the Queen has been Head of the Commonwealth in a position that has been far from simply ceremonial.
"The Queen has given her role some substance through Commonwealth Day, Christmas Day broadcasts, and her relationship with the Commonwealth Secretariat," says Prof Murphy.
"She has made a point of attending every Commonwealth summit meeting except 1971 when British Prime Minister Edward Heath advised her not to attend because of a row over Britain selling arms to South Africa.
"The Queen made it clear that she was upset that she could not go as she felt it was her duty to attend."
Reader Dennis Green in Brisbane, Australia, is full of praise for the Queen.
"Although there is a number of people who want Australia to become a republic, she is still highly regarded and respected.
"She represents an era of times gone by and yet people love her today."