Chance Miller, 9to5Mac:

The 12-inch Retina MacBook was first introduced during Apple’s March Event in 2015, with Apple touting it as the thinnest MacBook to date. It ushered in a new era for the MacBook lineup with a USB-C port and butterfly keyboard design.

And from this 2019 farewell when Apple discontinued production:

From trivial changes like space gray/gold finishes and display lids too thin for backlit Apple logos to futurist new features like automatically booting up when the lid is opened and a giant Force Touch trackpad without the diving board click button, the MacBook introduced changes that now outlive the machine.

A groundbreaking machine, in terms of design. It’d be interesting to compare the benchmarks of the 2015 MacBook with the similarly priced M1 MacBook Air. One additional USB-C port, way better battery life, and about a million times more processing power.