So what does this history lesson have to do with YouTube? IP (the Internet Protocol) is the protocol used to communicate data across the Internet in the same way telephones connected conversations over a century ago. Each connection has an IP address that works like a telephone number. Just like telephone numbers, these IP addresses need to grow to accommodate all the new people coming online. The problem is that IPv4, the current version of the Internet protocol, uses a 32-bit address and those addresses are running out of space -- fast. In 2000, Internet users had consumed 50% of IPv4 address space. Today, IPv4 has less than 10% of addresses available. When address space runs out, users will have to share addresses, because there won't be enough to go around.
But there is hope. IPv6 has a vastly larger address space (128-bit) and allows everyone to have an incredibly large number -- 2^64 or more -- of personalized IP addresses for all their devices (think of it as having a whole telephone exchange in your home). Not having to share IP addresses is good for users because it means better, more relevant information can be delivered to them whenever they want it. It's a win for openness and new applications because any device can connect directly to any other device on the Internet. It's even a win for security, because it's harder for hackers to find your computer and attack it. But up until now, IPv6 still hasn't gotten as much traction as IPv4. And content creators and users have yet to adopt it on a wide scale.
Since the very first announcement of ipv6.google.com (IPv6 connection required; if you don't have it, ask your ISP to deploy it), we have been committed to supporting IPv6 and have steadily added IPv6 support to more and more services. The service most requested to have IPv6 support has unquestionably been YouTube. Given all of this, we're proud to make YouTube available over IPv6 and to begin streaming videos from a select number of sites worldwide to our Google over IPv6 partners. With YouTube on board, we now have a significant amount of content delivered on IPv6 and a real audience/traffic for it. This is a good day for YouTube, our users and for an open and accessible Internet.