These diagrams are named after Kaoru Ishikawa, a Japanese professor and influential quality management expert. They were first started to be used in the 1940s, and are considered to be one of the seven important tools in quality management. They are alternatively referred to as Ishikawa diagrams, fishbone charts, cause and effect charts, or root cause diagrams. They are most frequently used in product design and manufacturing, analyzing defects or deviations and trying to identify the root causes.
The problem is stated in a box to the right of the diagram, and each major branch is devoted to some of the key issues that could have caused the problem. Major issues are generally grouped by people, materials, machinery, processes, measurements and external factors. But there is a whole art to grouping these major branches, and people have come up with standard groupings such as the 8 Ms, the 8 Ps, or the 4 Ss.
The 8 Ms (used in manufacturing)
- Machine (technology)
- Method (process)
- Material (Includes Raw Material, Consumables and Information.)
- Man Power (physical work)/Mind Power (brain work): Kaizens, Suggestions
- Measurement (Inspection)
- Milieu/Mother Nature (Environment)
- Management/Money Power
- Maintenance
The 8 Ps (used in service industry)
- Product=Service
- Price
- Place
- Promotion/Entertainment
- People(key person)
- Process
- Physical Evidence
- Productivity & Quality
The 4 Ss (used in service industry)
- Surroundings
- Suppliers
- Systems
- Skills
There is a great Wikipedia article on Ishikawa Diagrams (link), which provides a lot of context, questions to ask in each branch, and additional resources and links.