Php change variable from a page [duplicate]

This question already has an answer here:

• passing hidden input value by using php [closed] 4 answers

I'm not sure if this is the right question for this hence i am not sure how it's called.

So basically what i have

<?php 

$word1 = "Something";

 ?>

is it possible from a browser to handle a variables e.g

<input value="Derp">
<button>Submit</button>

with a form or something?

As in if i fill the value with lets say Orange the $word1 becomes orange?

or does this happen trough php form and a database?