Jujitsu is a combination of all martial arts techniques to make a form of defence. It formed during the Sengoku period of the Muromachi period when Samurai warriors were no longer paid to fight in wars (being a samurai was a high paying job). Strict Laws were made by the Tokugawa shogunate to hopefully reduce war in Japan, this made swords and all weapons illegal for everyone but the Samurai, so martial arts schools that taught unarmed combat grew in popularity throughout the period.
Jujitsu mainly focuses on disabling, disarming and on the rare cases, killing your opponent. To do this you would using striking, throwing, restraining,