Bootcamp for Mac was released with Mac OS X 10.5, or Leopard, in 2007. It allows all Intel-based Mac computers to run Windows. This is handy for anyone who wants to run both Mac OS X and Windows without having two computers. In order to run Bootcamp, you do have to partition your hard drive, which means you will have smaller hard drives in both Mac and Windows. However, it is worth it when you can easily switch Bootcamp to Mac or Windows.
Press the power button on your Mac to turn it on or restart it. To restart your Mac, hold down the power button until it turns off and starts back up.
Hold down "Option (alt)" while the Mac starts up. A gray screen with two computer icons should appear. One is labeled Windows one is labeled Macintosh.
Select the Macintosh computer icon and click on it. This switches Bootcamp to Mac so your computer will start up in Mac OS X.
Set up a default OS with which to start your Mac by going to "Start up Disk" in System Preferences and choosing Mac or Windows.
Always save your work before restarting your Mac.
Windows must be installed on your Mac for Bootcamp to be able to switch between Windows and Mac.