An interval is a connected piece of the real number line which may be open or closed at either end.

An interval is a connected portion of the real line. If the endpoints a and b are finite and are included, the interval is called closed and is denoted [a, b]. If the endpoints are not included, the interval is called open and denoted (a, b). If one endpoint is included but not the other, the interval is denoted [a, b) or (a, b] and is called a half-closed (or half-open interval). An interval [a, a] is called a degenerate interval.

bisection | closed interval | half-closed interval | interval arithmetic | limit point | line segment | open interval | pencil | ray | unit interval

Interval

middle school level