The Trust Policy Module (TPM) ensures that you are booting the correct operating system. This is good because it stops you from booting an attacker's software. The process of verifying something like an operating system or application is called **attestation**. But what if I want to boot the wrong operating system? Technology like this is used to lock down a vendor's product and take freedom from the user. This is what creates the desire for "jailbreaking" Apple products.