I've seen so many posts along the lines of "I'd like to one-specific-thing for my one-specific-situation when it comes to buttons in HTML.
If I may, I'd like to get a professional take all in one post, here:
When making buttons in HTML, what situations lead to:
<a>
being the best answer?<button>
being the best answer?<div>
being the best answer?<input type='button'>
being the best answer?