What are sock blockers and mitten blockers used for?

What are sock blockers and mitten blockers used for?
To find out the answer to this question, just look at this photo.

In the photo you see two knitted sock. The right toe is dried on the fabric, the left toe is dried on the blocker.
Larger.

The difference is obvious.

The same is true for mittens. On the right, the mitten, which dried without a blocker, left the mitten, which dried on the blocker.

As the saying goes, it is better to see once than hear a hundred times. These photos, better than any words, show that blockers are the best tool for preparing and demonstrating knitted socks and mittens.