From Wikipedia: In October 1945 Pollock married American painter Lee Krasner, and in November they moved to what is now known as the Pollock-Krasner House and Studio at 830 Springs Fireplace Road, in Springs on Long Island, NY. Peggy Guggenheim lent them the down payment for the wood-frame house with a nearby barn that Pollock converted into a studio. There he perfected the technique of working with paint with which he became permanently identified.
Pollock described this use of household paints, instead of artist’s paints, as "a natural growth out of a need." He used hardened brushes, sticks, and even basting syringes as paint applicators. Pollock's technique of pouring and dripping paint is thought to be one of the origins of the term "action painting." With this technique, Pollock was able to achieve a more immediate means of creating art, the paint now literally flowing from his chosen tool onto the canvas. By defying the convention of painting on an upright surface, he added a new dimension by being able to view and apply paint to his canvases from all directions.