It puts a duty on all businesses not to trade unfairly, and will be policed by Trading Standards, which will prosecute offenders.
The new legislation outlaws information which, even if it is factually correct, deceives the average consumer into making a transaction he or she would not have taken otherwise.
It also puts a duty on businesses not to conduct aggressive sales practices, such as harassment, coercion and undue influence.
It stops retailers advertising products knowing there is insufficient stock to meet demand and falsely claiming customers would get a better deal if they sign immediately.
In all, 31 specific practices will be banned.
However, the rules do not extend so far as allowing disgruntled customers to claim compensation when businesses treat them unfairly.