For most of the people Karate is just a generic term for all martial arts that use kicking and striking.
This is not entirely correct ! Karate is a Japanese traditional martial art and it is not the same with other stand up martial arts like Taekwondo ( Korean ) , Kung Fu ( Chinese ) , Muay Thai ( Thai ).
Karate means literally Empty Hand and it was introduced in Japan by Gichin Funakoshi , who is considered the father of Karate .
How did Karate get to Okinawa ? According to legend, in the sixth century A.D., the Indian monk Bodhidharma traveled from India to China to teach the Liang dynasty monarch the tenets of Zen Buddhism. To endure this arduous journey, he developed the physical and mental powers for which he was later renowned.
These methods then later were borrowed by the people from the Ryu Kyu islands ( today Okinawa ) and further developed in many different styles.
 Some of the most known Karate style today are : Shotokan, Goju Ryu , Shito Ryu, Ishin Ryu and of course Kyokushin Karate.
The differences between these Karate styles are mainly how techniques are executed but also how kumite ( fighting ) is conducted. Some Karate styles teach non-contact or semi-contact fighting.
  In Kyokushin Karate we are ferm believers in contact type of kumite !
One can not learn to fight and therefore efficiently defend himself if training is done without contact. Of course the level of contact varies from very little contact for kids and beginners to full-contact for advance students.