# Crisp edges on subsurface modifier

Im trying to figure out how to make crisp edges on my mesh, without using loop cuts, which affect my mesh. As seen in the example on top of the model, I deliberately added a bump and on the side, I extruded a section inwards. Now when I add the loop cuts to give it a more crisp edge, the loop cuts which go around my model, also affect my object making it to deform. I tried the Edge Crease method, but the extruded section remains like a circle shape, and not rectangle which I'd like. Any suggestions how to get a particular section more crisp with out affecting the rest of the mesh?

Thank you.

to make an edge sharp, select the edge then goto Edge > Mark Seam or hit Shift E. enter a value between 0 and 1, 0 being not at all sharp and 1 being very sharp.