This is the simplest loop to tie in the end of a cord and is most frequently used when in a hurry, as when fastening a parcel.  It is quite versatile and can be used for a number of purposes.  If you wish to hang something heavy on it, though, it might be wise to make a different choice as it can be hard to undo after loading.

1. Make a bight in the cord, allowing a reasonable length of the line to be doubled.

2 & 3.  Tie a thumb knot, as before, with the doubled bight and pull the bight to tighten the knot.