Okay, to really get your head around phase, we need to move beyond the on/off perspective we just outlined. Phase is quite literally a relationship of degrees. In other words, our “out of phase” sine wave has a 180° phase relationship to its mirrored counterpart. Were we to gently move our duplicate sine wave through all degree positions in the phase relationship, we’d encounter different degrees of cancellation, and therefore different degrees of amplification and attenuation — from silence to peak volume and everything in between.
If you sample someone else’s music, make sure you’ve covered all your bases too. Reach out to the original songwriter to discuss splits and obtain a mechanical license to use their sample in your music, and then register and administer the percentage that you both agree upon. Don’t find yourself in a sticky situation — do your homework and know how to properly go about using samples.