Any system or hardware which was not manufactured by Apple for Mac OS is made to run the Mac OS X, such a setup is known as Hackintosh. Ie: Any non-apple hardware that is made to run Mac OS X is called as Hackintosh.

Is it Legal to be a Hackintosh user?

Unlicensed or pirated software is illegal, in that view Mac OS X from and after Mavericks are free, so it can be said to be licensed in a way. So it’s not illegal. But Apple doesn’t encourage or support the Hackintosh project or community, neither making a Hackintosh is against Apple’s EULA.Apple know there are Hackintosh projects going on, but they never tried to stop , again a partial green signal

How it’s done?

Since apple doesn’t make their osx to run natively on non-apple hardware, there are some works which can be termed as hacks are done to make it live.Usual Hacking approaches are Kernel hacks, custom bootloaders and emulators, line DVD and virtual machine concepts.

The Hackintosh Projects or  Communities

Here iI list some communities that focus on helping one another to configure, build, and troubleshoot Hackintosh systems. Listed Hackintosh communities such as the following may be useful to you: InsanelyMac Tonymacx86
OSXLatitude AMD OSX HACKintosh
MacBidouille iATKOS Root86
Hackintosh DE OSx86 ES