HTML icon links – button or <a> with CSS icon

  css, html, hyperlink, icons, symfony

This is a newbie question I’m afraid but hey, we’ve all got to start somewhere and I’m going round in circles trying to google this.
How do I create a bar of icons that do certain functions, for example log in/out, print a report, go to homepage etc. Very much like the icons on the top right of this page that link to the inbox, achievements, help center, etc.
Do I use link in the html and use CSS to style the icons?
Or do I use a button?
I’m using Symfony if that makes a difference.
Thank you in advance to any kind helpers.

Source: Symfony Questions