https://www.techradar.com/news/mobile-computing/laptops/best-ultrabook-18-top-thin-and-lights-1054355

The times, they are a-changin’, as Bob Dylan would say, and for laptops that means they’re getting thinner and lighter, but also faster than ever before. That rings true for nothing else more than it does the best Ultrabooks around. No thicker than 0.8 inches (2cm), these notebooks are as much about performance as they are portability. So not only will you not have to worry about your battery dying on the road, but you also won’t run into any ‘Not Responding’ errors. 

Of course, the Ultrabook specification was created by Intel to give the MacBook Air some much-needed competition back when it had none in 2011. Now, the MacBook Air has so many rivals that it’s a wonder Apple hasn’t updated its massively popular machine in three years. Perhaps it’s for that reason that the best Ultrabooks have gained so much traction recently. All running Windows 10 and coming from a wide range of manufacturers, these featherweight clamshells bear distinct innovation we haven’t seen from Cupertino in quite some time.