This is one of my top-10 favorite knots. I use it to secure a rope around an object, especially to bind several objects together. When dressed, and then the two tails are separated and pulled apart hard, the rope has a lot of tension on it and remains that way. However, it can still be loosened relatively easily. If it needs to be extra-secure, back it up with a square knot.
I use it as basically a latch/clasp for securing a box lid to the box.
It is also used as one of the basic knots in cable lacing, to ensure a bundle of wires stays neatly secured together. It's depicted on this page under the section "Method 2".
This is ABoK #1695.