The emerging low Earth orbit (LEO) mega-constellation networks, planned to be composed of thousands of satellites, have the potential to connect all through their global footprint and bridge the long-existing digital divide. This talk will focus on the communications and networking aspects of these mega-constellations and their integration with the terrestrial networks. The associated communication and networking problems will be investigated along with potential remedies such as the use of distributed massive MIMO and high altitude platform station (HAPS) systems. The talk will conclude with an overview of the open issues and future research directions.