Free trade and service deals between the China's Southern province of Guangdong and Hong Kong and Macao go into effect.
These will include agreements on equal treatment for all investors and investments for the first time, as well as negative lists, in a bid to promote further economic integration between the Chinese mainland and the two special administrative regions.
Also taking effect are regulations on Internet usernames, which ban deliberately misleading names, names linked to terrorism, and other accounts involving violence, pornography and other violations.
Another area that will see change is the law governing government procurements, with stricter monitoring measures coming into force which aim to reduce room for corruption.
Other newly implemented rules include regulations on environmental protection, such as Land Protection and Management in the Hebei Province, and air pollution control in Tianjin and the Anhui Province.