A figure-eight loop (also Flemish loop or Flemish eight) is a type of knot created by a loop on the bight. It is used in climbing and caving where rope strains are light to moderate and for decorative purposes.
The double figure eight is used to put a loop in the end of a rope, or around an object. It is relatively easy to tie and is secure, but can become difficult to untie after heavy loading, and can jam badly in any rope type.
Read more about Figure-eight Loop: Tying Methods