Have you ever wished you could use the Brush tool (B) to paint selections in Photoshop? Wouldn’t that be easier than the Lasso tool? Also with the Brush, you could use hard and soft edges to vary the hardness of the edges (which is like feathering). Imagine taking that a step further and varying the Opacity of selections, say 50% over here and 80% over there. That’s a nice pipe dream, no? But wait; before you send off a feature request to Adobe, I have to spill the beans. We have always had that tool. It’s called Quick Mask, and it’s everything that I just described. Press the Q key to go into Quick Mask mode. Use your Brush however you like. Press Q again and the brushstrokes become selections. And if you already have a selection in place, pressing Q toggles between a (masking) brush and a selection. 

This tip previously published in Colin Smith’s Photoshop Tips column, in the February, 2019 issue of Photoshop User magazine.