Nesting is a fundamental and very commonly used programming construct. In many cases, the wise use of nesting contributes significantly to a programming team's elegantly designing a solution to a difficult problem. However, the ease with which nesting constructs may be created and the essentially unlimited depth and breadth to which they may exist also enable a programming team to create structures which may be extremely difficult to understand and maintain. In this paper, we examine nesting and nesting metrics. In particular, we discuss nesting and complexity; we give a new definition for the scope of a selection statement; we define simple and precise metrics for nesting depth and breadth; and we present a new nesting concept, the nesting tree.