how to make predefined tags/code in html or css : <p>Let's say I have this html code:</p>

<pre><code>&lt;h1&gt;My website&lt;/h1&gt;
&lt;p&gt;Welcome to my website&lt;/p&gt;
</code></pre>

<p>Let's say that I want to put that on pretty much every page of my website without copy and pasting the same thing every time. How would I do that? </p>

<p>I'm also open to doing this in javascript but would prefer html or css.</p>
