Spend any time working with post-processing applications, and you will probably end up using blending modes sooner rather than later. They're incredibly useful and fundamental to most workflows, but how do they actually work? This highly informative video will dive deep into the theory behind blending modes and how they work.
Coming to you from Filmmaker IQ, this excellent video will show you everything you could ever want to know about blending modes in Photoshop. At their core, blending modes are simply mathematical formulas that tell Photoshop or a similar application how to take RGB data from two layers and combine it. These formulas are carefully tailored to provide different aesthetic results. While you of course don't need to memorize a few dozen math equations to work with blending modes, seeing how they operate under the hood and getting an intuitive feel for how the most commonly used modes combine data can help you to better choose the proper one and use them to make more powerful results and explore creative ideas. Personally, I'm interested to see if we'll eventually get some new formulas and blending modes one day. Check out the video above for the full rundown!