Closed Dot Vs. Open Dot

When an inequality that has been graphed has a closed dot it could mean three things.  These three things are that the inequality is equal to, greater than or equal to, or less than or equal to.  When the dot is open, it means that it is greater than or less than, but never equal to.  So if an inequality has an equal to sign,  you know that it must always have an open dot instead of closed.