The Windows 7 loader is a tool created by pirates and hackers for freely acquiring Windows 7 that functions like a genuine copy. It makes changes in the BIOS emulating the SLIC, making the system seem pre-activated like an OEM.
OEM stand for Original Equipment Manufacturer. Big computer manufacturers sell their products with the pre-installed, pre-activated versions of Windows. Every one of these manufacturers has their own master product key for Windows and the information tied to that key contained in the BIOS. Pirates have learned to exploit this as a vulnerability to make a computer on which the loader is installed seem like one of these products. The loader works by altering the BIOS of the PC, making it match the data of the unique encrypted information of the genuine license.
Using a Windows 7 loader can be very risky because it can install rootkits and malware that completely take control of a PC without the user even being aware of it. Using hacking tools and unlicensed software is also considered as crime, therefore liable for prosecution. The use of loaders and diverse hack tools for pirated software is widespread due to the fact of low standards of life and the undefined laws and regulations in many countries.