An interval can be denoted in different ways. One way is the interval notation, using and
The interval above can be described with an inequality as
where indicates that the endpoint is included and that it's not. The inequality can be translated to interval notation where indicates that the endpoint is included and that it's not.
The interval can then be read as
all numbers greater and equal to and less than . For more examples see the table below.
Note that if the variable only has one limit, the other is infinity and is not included in the interval.