Simple VM that allows booting from folder or disk

I was wondering if there was a very simple and free virtual machine that would allow you to boot from a folder or disk image that couldn't damage my hard disk. I am using a MacBook and am looking into operating system programming. I found a tutorial on the internet that looked promising. I want to try this but using a VM instead of actually booting from a disk. If I made a folder or disk image containing the boot.bin file and wanted to try the OS I made (while booting from a folder or disk image, not a disk), is there a VM that would let me do it? I have no previous experience with virtual machines. I also want to be sure my hard disk would not be damaged.