Masking with Refine Edge + Calculations in Photoshop CS5

[millertime6888]

Like I know when you use the lasso or pen tool to make a cut out selection you can use refine edge to smooth the edges but whats the mask doing here? Why make a mask?

[invalidacess]

@millertime6888 he made the mask so he can pass the image unto a different background. u need the mask there so that u dont take the background shes in.

[millertime6888]

What's a mask for? Why is this helpful. Sorry if it's a stupid question but I'm just trying to teach myself how to use photoshop.

[invalidacess]

@millertime6888 a mask is basically to hide or show things. think of it as the eraser tool but with the mask if u went too far u can undo it by painting it white. White shows the picture and black hides.