Popping was derived from the earlier Boogaloo street dance movement taking place in Oakland, California during the late 1960s, the Boogaloo dance form incorporated techniques of soulful footwork steps, arm movements, stop-motion animation, the robot, & posing hard - which contracted muscles during robotic poses to the music of Funk. Throughout the 1960s and 1970s - Boogaloo groups in Oakland, CA such as One Plus One, the Black Resurgents and the Black Messengers would help popularize the dance. Early Boogaloo movements would inspire groups throughout the San Francisco Bay Area and eventually spread to Fresno, California in the 1970s and popularized by Samuel "Boogaloo Sam" Solomon and his crew the Electric Boogaloos. It is based on the technique of quickly contracting and relaxing muscles to cause a jerk in a dancer's body, referred to as a "pop" or a "hit". It is also known as Posing Hard from the Boogaloo tradition, this technique was innovated by the Boogaloo group, the Black Messengers from Oakland. When performed correctly, each "hit" is synchronized to the rhythm and beats of the music. Popping is also used as an umbrella term to refer to a wide range of closely related illusionary dance styles such as strobing, liquid, animation, twisto-flex, and waving. Dancers often integrate these styles with standard popping to create a more varied performance. In all of these subgenres it appears to the spectator that the body is popping. The difference between each subgenre is how exaggerated the popping is. In liquid, the body movements look like water. The popping is so smooth that the movements do not look like popping at all; they look fluid. The opposite of this is strobing (also called ticking) in which the movements are staccato and jerky.