The Point buy or purchase method for generating ability scores in Pathfinder is described below.
Generating ability scores
Each character receives a number of points to spend on increasing his basic attributes. In this method, all attributes start at a base of 10. A character can increase an individual score by spending some of his points. Likewise, he can gain more points to spend on other scores by decreasing one or more of his ability scores. No score can be reduced below 7 or raised above 18 using this method. See Table: Ability Score Costs for the costs of each score. After all the points are spent, apply any racial modifiers the character might have.