What is =~ operator in elixir : <p>From the <a href="https://elixir-lang.org/getting-started/sigils.html" rel="noreferrer">documentation</a> I understand how <code>=~</code> operator works to match regex, but I don't understand the general use of this operator. </p>

<p>For example, what does <code>"foo" =~ "foo"</code> mean? 
How is it different from <code>"foo" == "foo"</code>?</p>
