Since 2011, local authorities are legally required to monitor the equality and diversity of candidates seeking election to county and county borough councils and community and town councils.
Mae gwahaniaethau ym mhroffil oedran plant a phobl ifanc sy'n gallu siarad Cymraeg rhwng Cyfrifiad 2011 a 2021 yn amrywio'n sylweddol rhwng awdurdodau lleol.