If you want to make electronics and sell them to people*, there are a number of regulations you need to follow. Some of them are RoHS and REACH, which deal with the restriction of certain substances in anything that is sold in Europe. If you put a CE mark on your product, which is required for selling electronic products in the EEA /EFTA (EØS), it is a declaration that your product complies with these standards (among others).
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