What is a string?!?

At a basic level, it's a sequence of characters (eg "this is a string literal"). see http://php.net/manual/en/language.types.string.php

String is sequence of characters

• $fruit = 'Apple';
• $vegetable = 'tomato';

For example you want to display it into list what you have bought

<ul>
   <li><?php echo $fruit; ></li>
   <li><?php echo $vegetable; ></li>
</ul>

In the real world solutions you will probably use some templating system.

If you are curious look at:

• https://twig.sensiolabs.org/
• https://laravel.com/docs/5.4/blade
• https://latte.nette.org/en/

The first one is often used with symfony.

The second one with laravel and the last one with nette.

If you ask why to use f.e. twig, let me rewrite my example it would look like this:

<ul> 
   <li>{{ fruit }}</li>
   <li>{{ vegetable }}</li>
</ul>

It has specific syntax which helps you write more concise and readable code