# Interval

### From Conservapedia

An **interval** is a connected segment of the real line. It is defined by taking two points, *a* and *b* with *a* < *b* that are the endpoints of the interval. Then the interval is the set of all points between the two endpoints, sometimes including the endpoints themselves. An **open interval** includes neither endpoint, a **closed interval** includes both endpoints, and when just one endpoint is included the interval is called **half-open** or **half-closed**.