Where can I get enzymes from?

Excuse me, I was wondering if you could help me understand where one might acquire enzymes. I've heard that they play a crucial role in many biological processes, and I'm curious about their sources. Are they naturally occurring in certain foods, or do they need to be extracted from other substances? Is there a specific place where one could purchase enzymes, perhaps a health food store or online retailer? I'd appreciate any information you have on this topic. Thank you in advance.