Non-Latin / non-ASCII characters don't render correctly

Symptoms

Non-Latin characters in a web page (for example: ß, 猫, ✌️) don't render correctly.

Cause

If a web page doesn't explicitly specify a character encoding, then the browser may default to a Latin character encoding that doesn't support non-Latin characters.

Resolution

If the web page is one that you control (i.e. it's your website), add the HTML element <meta charset="utf-8"> to the page's <head> to set the character encoding to UTF-8, like this:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
  </head>
  <body>
    ß, 猫, ✌️
  </body>
</html>