Standards are established norms and agreed-upon ways of doing things and designing things. Engineering standards make sure that safety needs are met, interoperability works out, and more.
Standards are created by committees within organizations -- from professional societies to government agencies.
Using standards means that you are following regulations in some cases and in other cases it means you are following a consensus on the best way of doing something; still yet, you may be doing everything you can to make your product marketable and safe.
Read more about standards from the NIST Standards Page and the ISO Standards Page.