Enable writing to NTFS hard drives for free in Mac OS X (including El Capitan!)

Windows uses the NTFS file system for its hard drives. Mac OS X can read files on NTFS hard drives, but it can't write files to them, which is a glaring omission. Attempting to drag a file into an NTFS drive in Mac OS X will only result in your mouse cursor turning into an error sign. Since many Hackintoshes dual-boot Windows and Mac OS X, being unable to share files between hard drives can lead to a lot of problems with file management. Fortunately, you can enable NTFS writing on OS X with relatively little trouble-- all it takes is a few drivers and 10 minutes of your time.