It is specified - a struct tag is just a string literal after a struct field. See <a href="https:&#x2F;&#x2F;golang.org&#x2F;ref&#x2F;spec#String_literals" rel="nofollow">https:&#x2F;&#x2F;golang.org&#x2F;ref&#x2F;spec#String_literals</a><p>If you use backticks, the tag must not contain another backtick. On anything but a struct tag, you could get by by concatenating literals, but that&#x27;s not allowed for struct tags: <a href="https:&#x2F;&#x2F;golang.org&#x2F;ref&#x2F;spec#Tag" rel="nofollow">https:&#x2F;&#x2F;golang.org&#x2F;ref&#x2F;spec#Tag</a> You could use double quotes instead of backticks, but that leads to a dark corner of escaping hell and an utterly unreadable mess.<p>Thankfully, the language strongly nudges you to very, very simplistic and light uses of struct tags.