It is the manufacturer who is responsible for ensuring that a product is safe. In order to assess the safety of products, the authorities together with the industry have compiled standards for different product groups.
The manufacturer produces technical documentation for the product. When the product has been developed and manufactured, the manufacturer produces a Declaration of Conformity. The product can be CE-marked when these documents are available.
Standards are often international and apply, at least, throughout the EEA. When a new product is developed, it is appropriate at an early stage to determine which standard the product shall comply with.