Every country in the Commonwealth has signed up to a shared set of values.
These include holding fair and free elections and respecting human rights.
In the past, some countries have been suspended from the Councils of the Commonwealth because they did not follow this agreement.
Zimbabwe was suspended for a year in 2002 because top politicians said president Robert Mugabe's supporters used violence to help him win an election.
A row at the 2003 summit in Nigeria led to Mr Mugabe withdrawing his country.