Communication and Security: Network structures

How do our devices connect to a router? And then how does that router connect to the rest of the world? Questions that have come as side thoughts for split seconds and vanish, never focused on to be explored and understood -- part of the many things taken for granted. 

Conceptually there are typical layouts of network setup in homes, but in the end the result is that they're in communication with each other or have the ability to reach each other (source). 

Ethernet connections use the 'Bus' layout whereas Wireless LAN connections would be generally conceptualized with the 'Star' layout. in which the central node is the Wireless Access Point (WAP). WAPs may be integrated into the router itself, but are not necessarily. Regardless the access point's responsibility to is to connect to the router. 

These layouts may also apply to the router whose responsibility is to determine where to forward data packets to other nodes or sub-networks -- as the internet can be seen as 1 enormous network. For network security, firewalls can be seen as the filter properties of each node. 

The vastness of the internet.

Yes, this is all quite summarized and general concepts, otherwise Network Security wouldn't be such a 'hot' job at the moment. At the very least I hope this is a starting point to asking more questions about how computer networks communicate and process data to one another.