The domain of a function describes all the possible x values
The range of a function describes all the possible y values
In describing your possible values use a parenthesis to show that the end value is NOT included and a bracket to show that the end value is included.
For example (3,7] means your possible values are between 3 and 7 but the 3 is NOT included and the 7 is included.
If the possible values extend to infinity express with (-infinity,+infinity) making sure you label positive or negative infinity and have a parenthesis