All products need to pass some sort of compliance testing and certification before they can be legally released to market. For most sectors, this compliance comes in the form of a mark on the product itself such as CE, FCC or an e mark (in the automotive industry).
There are different compliance rules in different parts of the world, so when a product is released world-wide, it needs to be measured against the various compliance requirements in each territory.
The mark indicating compliance in EU and the UK is the CE mark. This mark indicates that the manufacturer has made a Declaration of Conformity (DofC), a self-certificate that indicates the standards that a product has been tested against. The DofC must be publicly and easily available.