Diffraction is something that can rob your images of sharpness, and as such, it is important to have a functional understanding of what it is and how to avoid it. This excellent video explains what diffraction is and how it varies based on different parameters.
Coming to you from ProAV TV, this helpful video will explain the concept of diffraction. You have probably noticed that very few photographs get taken past an aperture of about f/11 or so, even if the photographer needed more depth of field. This is almost always due to diffraction, which will cause a softening of the image as your aperture gets narrower and which is why you should try to avoid ever stopping down your lenses to very small apertures like f/22 or f/32.
Diffraction is a physical phenomenon, and as such, there is no way to engineer our way around it. And while you do not need to understand the complex physics behind it, it is important to have a practical knowledge of when you can expect it to appear and what you can do to work around it. Check out the video above for the full rundown.
If you want to calculate the diffraction limited aperture for your specific camera, check out this helpful calculator from Photo Pills.