Thanks Blessings Barbara, you only missed out gasket, this isn't anything to do with stopping leaks in pipe joints, they are the lines used to hold the furled sail against the yard, they can be just a straight line and made off with a reef knot, but we use a line as described by Bert, draw the free end through the eye splice and make off with a slippery hitch, harder for the trainees to get wrong!
Oh and Brarbara, you can in theory splice braided line, but I've never seen it done. Normal line is laid.
An old salt I knew used to describe a back splice as "Looks like a bullock's prick and about as useful." refering to the problem that a back splice will jam in a block. On the subject of splices, the ability to do a long splice used to be a test for rating as AB, same old salt told me of a lad who reckoned he was an AB and when given two lengths of line to demonstrate his ability came back with a short splice two feet long.