Gemba:

Gemba is a Japanese term meaning "the place where the truth can be found." Others may call it "the value proposition."

In quality management, gemba means the manufacturing floor and the idea is that if a problem occurs, the engineers must go there to understand the full impact of the problem, gathering data from all sources. Unlike focus groups and surveys, gemba visits are not scripted or bound by what we want to ask.
Glenn Mazur introduced this term in the Quality Function Deployment (QFD) (a quality system for new products where manufacturing has not begun) to mean the customer's place of business or lifestyle. The idea is that to be customer-driven, one must go to the customer's gemba to understand his problems and opportunities, using all one's senses to gather and process data.
Toyota have a very high proportion of their management on the shop floor (the Gemba) so that supervisors can be intimately involved in quality issues as they arise. Their presence in the Gemba informs their decision making and speeds resolution of problems. This Gemba attitude is driven by the belief that all customer value is created in the Gemba and it is therefore the qualities of the Gemba which will determine the success of the company.
Japanese detectives call the crime scene a gemba.