I will attempt to describe confinement without the jargon that pervades these pages. The original environment of the Factory ideas was an operating system kernel on a large shared computer. The primary motivating scenario was two parties:
There has been recent interest in a computing utilities such as inspired the original idea but there is also use for such confinement in computers as commonly employed now. In a personal computer the owner is more likely to assume the role of Q, wishing to be assured that his secrets will not leave the computer by channels unknown to him. To the degree that the computer and kernel are tamperproof the rights of P are protected as well. This approaches the common idea of DRM when P brings “content” as well as programs.
Here is a more detailed description of the factory with only a bit more jargon. See this for the history and development of the confinement ideas.