title: Can I just make up attributes on my HTML tags?
body: <p>Am I allowed to add whatever attributes I want to HTML tags such that I can retrieve their value later on using javascript? For example:</p>
  
  <pre><code>&lt;a href="something.html" hastooltip="yes" tipcolour="yellow"&gt;...&lt;/a&gt;
  </code></pre>
  
  <p>If that's not going to work, how would you store arbitrary pieces of information like this?</p>
  
  <p><strong>Edit:</strong> Since it appears that making up HTML attributes isn't technically valid, I've rephrased the second part of this question into its own question here: <a href="https://stackoverflow.com/questions/432174/">How to store arbitrary data for some HTML tags</a></p>