What is sampling in music?

Sampling is stitching existing musical work together with another work-in-progress normally inside a DAW (although this can also be done using a hardware workstation). To successfully do that you need permission from whoever owns both the sound recording copyright and the publishing side of things otherwise you will get sued for copyright infringement.

The cons of sampling​

If you take the route of manipulating other people's recorded music expect them to demand massive cuts of at least more than half of the future earnings during the sample clearance process. They can do that because already the ball is in their court and even if you were to remove the music sample you used there's a high likelihood that the record itself will lose its vibe altogether.

Sometimes it's also a bummer when you come across an incredible sound, only to find that the original recording artist won't let you successfully go through the licensing process due to their personal prejudice against you. That's why it's important to build relationships with professional musicians early on while they still don't know who you are so that they aren't as likely to decline your offer down the road.

Another disadvantage of sampling is that it can push back scheduled release dates, throwing a monkey wrench into the works and destroying all your careful planning. This can happen if the reworked sample contains too many different entities to go through.

Can you sample your own music?​

The answer is simple really—if you no longer own your music or if you sold your music publishing, you’ve got to seek consent from the copyright holder to interpolate it in another work as everyone else would. Otherwise, you may be hitting up the courtroom for copyright infringement. Nevertheless, if you're still lucky enough to hold on to ownership (and assuming there are no previous samples, and there are no other collaborators) feel free to go ahead and sample yourself with impunity.