Originally Posted by Barb44

Squaring is trimming edges to make a perfect square or rectangle. It can be done to a block or a whole quilt.

Blocking is wetting the quilt top and pinning it to something solid (like a carpet) to the size you want. The fabric will stretch a little when wet, or shrink when it dries. I think you can also use a steam iron to block it, although I have never done it. I always square my puilts if necessary.