A fixed loop, very safe. You can use it when climbing and lifesaveing etc. If your life depends on this knot, you should do an extra knot to make it safer. Otherwise it will not be safe enough, especially if the rope is new. Often learnt by thinking of the end as a rabbit, and the loop as its hole, and as Elma Fudd would say: The wabbit gows up, out of his hole, wound the back of the twee, and back down into his buwwow!

The Sheetbend is a knot that you use to tie two ropes together. Good both for thick and thin ropes. Easy to untie. Use the Sheetbend (Becket Hitch) when you hoist a flag, and the loop already exist. The Slipped Sheetbend is even more easy to untie, just snatch the right end.