The Sheetbend is commonly used to tie two ropes of unequal thickness together.
The thicker rope of the two is used to form a bight, and the thinner rope
is passed up through the bight, around the back of the bight, and then
tucked under itself.
The knot should be tied with both ends coming off the same side of the
bend, as illustrated here. However it can easily be accidentally tied with
the ends coming off opposite sides of the bend, when it is known as the
Left Handed Sheet Bend. The Left Handed Sheet
Bend is to be avoided as it is less secure.