Because Kaizen comes from Japan, a lot of the words it uses are in Japanese. Pretty much every discipline has a shorthand for complex concepts; some of the ones I use here just happen to be in Japanese. So, I've defined them here.
Gemba is a Japanese term that literally means “where the action is.” For instance, a reporter who is on the scene of a crime will be reporting from the gemba of the crime.
In Kaizen, the gemba is the place where the business value is created. For manufacturing, this is process steps in which new features that customers value are added. So, for instance, a warehouse adds no new features and therefore is not the gemba; a production line does, and is the gemba. A sales office probably is not the gemba, but the room in which a sales meeting takes place is.
The Kaizen concept of Morning Market is of a shared opportunity to see what went wrong the day before. Classically, in Kaizen manufacturing, the pieces that failed QA are brought out and are reviewed by the whole manufacturing team, so that everybody can see what happened and everyone can put in their two cents as to what went wrong. It’s not a time for blame, but, instead, a time for learning — the goal is to identify flaws in process and improve them (an operator who did their job wrong might, for instance, highlight a flaw in a training process).
Muda is, in Kaizen, waste. The term is from the original Japanese, and alliterates with the other two major process flaws, mura and muri. There are traditionally seven kinds of muda waste, outlined in the Toyota Production System:
Of these, inventory and defects are often the most-emphasized.
Mura is best expressed in English as “unevenness” — but it’s not a local trait, as in “the surface of this rock shows mura,” but more a global trait “our effort level shows mura,” “our inventory levels show mura,” etc.
Wide variations in inventory or work effort show inefficiency. Product should be produced at predictable levels, and for sale as quickly as possible. This avoids having cash tied up in product you’re waiting to sell, or in overtime to make product to sell. An efficient production process is smooth and predictable, and has as little inventory as possible both entering the process; excess stuff doesn’t have to be bought to keep the process flowing, because progress and speed are predictable, so it’s easy to have enough; and excess inventory doesn’t have to be kept after production, because everything is sold quickly.
The main ways to minimize mura are through just-in-time procurement and production, and through the use of a kanban scheduling system.
Muri is a Kaizen term often translated as overwork, overburden, or strain. It’s the process flaw of asking too much of a step in the process. This step in the process can be mechanical — demanding a drill make a hole too quickly, for instance — or it can be human — working an employee too many hours, or asking them to monitor too many steps in a process. The effect of muri is to decrease quality and (just as importantly) sustainability of a process.