After the final fermentation comes scoring.
Some breads like pizza, ciabatta, braided loaves, bagels and bialys or focaccia and flat breads are baked without scoring. The shape of those breads allows for expansion without bursting.
Other breads like boules or batards and baguettes should be scored. Although scoring does give us a chance to give the bread our ‘signature’ and add a beautiful design, scoring has a more important purpose.
When scoring dough, we intentionally create a weak spot out of which the dough can expand easily. If a loaf of bread is not scored, then it may burst open at its weakest point which most of the time will be at the seam on the bottom.
When it comes to artistic scoring there are no rules. Your imagination is the limit. The important point to remember is the depth of the cuts. The deeper you cut a dough when scoring artistically you risk it bursting out at that cut and ruining your flowers or whatever you decided the design to be.
If your dough has over proofed and is a bit weak, then it might be a good idea to not score it at all as the cuts will make it deflate rather than puff up!
To score bread ideally you should use a very sharp object like a razor blade (preferably in a lame for good handling possibility).
A serrated knife would also work.
Watch the video here