Reduction of hazardous substances, also known as RoHS, is a piece of legislation created by the EU in 2003 to reduce the harmful effects of dangerous substances to people and the environment.
Still, there are many individuals and some large-scale distributors who continue to use non-RoHS parts. This is because RoHS compliance can be difficult to fully comprehend and is generally inconvenient and expensive even at the governmental level.
Some of you may wonder why we have to buy RoHS goods instead of cheaper non-RoHS components? In fact, using non-RoHS components is a legal matter: you have to use RoHS parts for any product if you want to do business in the EU. This is because all EU products have to conform to the European standards, denoted by the CE mark on European products, if they are to be sold. A company found to be selling non-compliant parts will be prosecuted, fined, and can even face the possibility of imprisonment.