After making a selection we’ll see a marching ants outline around the object, but this edge is initially very jagged and abrupt. With real-world objects like the macaw here the edges are usually much softer and more fuzzy. So we need to improve the edge to make our cut- out more precise. This is where the Refine Edge command (Select>Refine Edge) comes in. When we run our selection through the command, it comes out infinitely better. The key setting in Refine Edge is the Radius. By increasing this we push the area of refinement outwards from the edge, forcing the command to look further afield for similar pixels to include or exclude. We can also paint with the Refine Radius tool (found at the side of the dialog box) to manually increase the radius in especially tricky parts of the edge like the feathers here.