Vessels- what are they?

Vessels are very long, tubular looking structures and are the characteristic conducting units of angiosperm xylem. There are several cells that make up this structure and they are all connected end to end in a row. The vessel element represent each of the cells of a xylem vessel which is equivalent to a tracheid. How are vessels formed? well vessels are formed when vessel elements that are close bond as a result of the disintegration of their walls