Other phones, however–and some carriers–don’t allow you to unlock your bootloader the official way, which means you have to wait for developers to exploit a security vulnerability if you want to root and flash ROMs. Nexus phones are all unlockable by nature, and many phones from Motorola and HTC allow you to unlock your bootloader through a similar process as the Nexus.
Whether you’re allowed to unlock your bootloader depends on the manufacturer of your phone, the model you have, and even your carrier. There are two kinds of phones in this world: Those that let you unlock your bootloader, and those that don’t.