Why do crackers (and some biscuits) have holes?

Because of this curious question that kept spinning in my mind today, I Googled and found a site called Today I Found Out which gave the answer to this and many more everyday questions that we easily brush off as trivia. I'm impressed with the site and added it to my Feedly RSS feeds.

So, I gather that the holes in biscuits are decorative while the holes in crackers are there for a reason(s) as explained by Today I Found Out:

In actuality, without these holes, crackers wouldn’t bake correctly. These holes allow steam to escape during cooking. This keeps the crackers flat, instead of rising a bit like a normal biscuit as the steam tries to escape; these holes also help to properly crisp the crackers.

A photo posted by @ionbuck on Mar 16, 2015 at 6:03am PDT