Square brakets mean a closed interval (dot), and round brackets mean an open interval (circle). so [-2,7) means so the closed endpoint includes the bound, but the open endpoint doesn't.
Often we'll receive questions that have a graph looking like the first picture I posted, with either circle or dot end points.
Also, sometimes we'll get a domain given as [-2,7).
I don't understand what these different brackets and end points mean. Please explain! Thanks