Now what...?

So, we have an IGP which lets all our routers see each other.
They're running IBGP which distributes reachability info for all the networks they're connected to.
EBGP is distributing this same reachability info to external peers.
And we're receiving prefixes from those peers and distributing them throughout our network.
Full Internet connectivity, no static routes...
... but it's a bit simplistic, isn't it?

So, we have an IGP which lets all our routers see each other.