What is cracked minecraft?

So, I've had paid minecraft since 1.2.5, and then around 1.5.1 I changed PC, I forgot my account. And then, a few months later, my friend said he can give MC to me for free.So, he inserted a disc into my computer and put it onto desktop. And then I could start playing, I could play multiplayer too.It wad 1.7.2.Is this some version of cracked minecraft? Someone tell me please!