This is the one of the simplest loops, although still quite strong and effective. It is generally better to use a figure-of-eight loop (either on a bight or rethreaded) as these are stronger. However, the figure-of-eight is a bulkier knot, and sometimes there is insufficient rope to tie it. In this case the overhand loop is a good substitute.
Also, the overhand loop is a better choice as a mid-line loop than the figure-of-eight, although the alpine butterfly should generally be used where possible.
|Take a bight of rope|
|Pass the bight back over the main part of the rope ...|
|... and then feed it up through the loop formed.|
|Pull tight and set the knot.|