Karate is primarily a standing/striking martial art. In Jiu-jitsu the focus is more on grappling and taking the fight to the ground thereby rendering a bigger, strong opponent less of a threat. Or simply getting away from an attacker. Although Jiu-jitsu does have some striking it is not our primary focus. Gracie Jiu-Jitsu has proven to be the most effective and most humane system of self defense, the only one in which a smaller person can defend successfully against a more athletic, bigger, stronger attacker. One of the reasons why this is possible is because its unique set of principles based in the philosophy of the founder of the art, Grand Master Helio Gracie. Another reason Gracie Jiu-jitsu is so effective is because it is trained with "aliveness" meaning it is pressure tested against resisting opponents regularly.