Internet

The planet is running out of IPv4 addresses that are used to identify specific routers, computers, and web servers. WashPo's Rob Pegoraro explains it all quite well, without dumbing it down too much and without confusing the hell out of me either. This was not an easy feat when it comes to the topic of network addressing, which can make even the best brain bleed. As a bonus for reading the article,you can click a link to learn what undecillion is.