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 $$\text{-}1\le x<2$$ where $\le$ 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. $$[\text{-}1,2)$$ The interval can then be read as all numbers greater and equal to $\text{-}1$ and less than $2$. 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.