Should an ampersand be URL encoded in a query string?

Question

For example I quite often see this URL come up.

https://ghbtns.com/github-btn.html?user=example&repo=card&type=watch&count=true

Is the & meant to be & or should/can it be left as &?

Answer 1

& is for encoding the ampersand in HTML.

For example, in a hyperlink:

<a href="/github-btn.html?user=example&amp;repo=card&amp;type=watch&amp;count=true">…</a>

(Note that this only changes the link, not the URL. The URL is still /github-btn.html?user=example&repo=card&type=watch&count=true.)

While you may encode every & (that is part of the content) with & in HTML, you are only required to encode ambiguous ampersands.