Overview
CE marking is the manufacturer's declaration that a product meets the EU rules that apply to it. The letters stand for Conformité Européenne. You see the mark on electronics, toys, machinery and many other goods sold in the European market.
The marking covers the relevant safety, health and environmental requirements. For electronics, those rules include RoHS, which restricts certain hazardous substances.
Self-declaration, not a seal of approval
For most product groups the manufacturer assesses conformity itself and then applies the mark. No authority hands it out, and it does not certify quality. For higher-risk product groups a third party called a Notified Body must take part in the assessment before the mark can be applied.
CE is not a quality mark and not a stamp from a government office. It is the manufacturer saying, on its own responsibility, that the product follows the applicable EU rules.
What stands behind the mark
Two documents support every CE marking. The EU Declaration of Conformity is the signed statement listing the rules and standards applied. The technical documentation is the evidence file the manufacturer keeps to back it up. For RoHS, that file is built to EN IEC 63000.