The plain HTML way is to put it in a <form> wherein you specify the
desired target URL in the action attribute.
<form action=" //google.com">
<input type="submit" value="Go to Google" />
</form>
If necessary, set CSS display: inline; on the form to keep it in the flow with the surrounding text. Instead of
<input type="submit">
in above example, you can also use <button type="submit">. The only difference is that the <button> element allows children.
You'd intuitively expect to be able to use
<button href=" //google.com">
analogous with the
<a>
element, but unfortunately no, this attribute does not exist according to HTML specification.