Imagine a flat where the router is located in the living room. Now you want to get access to the internet from the office room with your notebook via your router.
But:
<ul>
<li>the office room is several meters and 2 rooms away</li>
<li>the wlan signal can't get through the walls and </li>
<li>you can't put an ethernet cable from the router all the way through your flat to the office room</li>
</ul>
How can you manage it to still get access to the internet via your router?