Isshinryu Karate is a style of Okinawan martial arts developed by Tatsuo Shimabuku, first taught publicly in the 1950s. While he was very much a part of the Okinawan martial arts community, Shimabuku became widely known by teaching US marines stationed on Okinawa. Shimabuku had at least 4 major teachers, but found (I believe) a common
Isshinryu is generally characterized in the United States by it’s basic upper and lower body exercises, and a series of solo forms, known as kata. Done empty hand, there a 8 kata, but there are also weapons kata. Depending on the lineage, there are 2-3 solo kata with a weapon known as a sai, and 3 kata with a staff, called a bo.
Despite these widely known characteristics, there is a great deal of other material which makes the style quite rich. Tactically, Shimabuku taught two categories of material. The first is clever self-defense techniques. He was a small man, approximately 5’2” tall, and around 130 pounds. The US marines he taught (and who had recently invaded his island) were MUCH bigger. His approach to being grabbed often takes advantage of this size disparity in surprising ways. While the style is known for the “basic exercises”, the aforementioned self-defense tactics comprise what might be known as the advanced exercises.
The second category of material is power generation. This is about punch way above your weight class. Some of these mechanics are familiar to most martial artists, such as proper alignment. And, careful attention to detail here can develop significant power. However, Isshinryu also teaches less widely known skills for power. These relate to one of the solo kata, called sanchin, but are also practiced in some of the basic exercises, and with partner drills.