Challenge 2 — Solution

Task: Create a variable called $favouriteLanguage set to "PHP", then echo
a sentence using double-quote interpolation that includes the variable's
value. Then echo the exact same sentence using single quotes, and
observe the difference in the output.

<?php
    $favouriteLanguage = "PHP";

    echo "My favourite language is $favouriteLanguage.<br>";
    echo 'My favourite language is $favouriteLanguage.';
?>


Output:
My favourite language is PHP.
My favourite language is $favouriteLanguage.

Notes:
- The double-quoted line substitutes $favouriteLanguage with its actual
  value, "PHP" — this is string interpolation.
- The single-quoted line outputs the variable name literally, dollar
  sign and all, since single quotes never interpolate variables.
- This is a real, practical distinction in PHP, not just a style
  choice — picking the wrong quote type is a genuine source of "why
  isn't my variable showing up" confusion for beginners.