Definitions

Context can shape and drive the design process of a building, as a standard you can either attempt to assimilate to or react against.  The context includes the all-important site, the culture of the users and the viewers, and not only the history of the place but its intended future as well.  Based on the context, a design can blend in thoroughly, or it can take the traits of the context and elevate them, or it can subvert the context and stand out or even risk being offensive.

Concept is like the plot of the design story.  Without a certain amount of deliberate action, a design can look cool but might lack a certain amount of integrity.  Concept isn't universally considered the be-all and end-all of the design process.  Some designers use it as a driving force for every decision they make, and designs made this way are usually coherent and legible in the end.

Diagrams are used to generate or analyze specific parts of a design, like the relationship of public to private areas, or the circulation path.  The useful thing about diagrams at the beginning of the design process is that they are simple enough to easily reconfigure for the generation of numerous ideas and schemes.

A parti is a quick and simple illustration of the underlying premise behind a design.  A parti usually includes aspects like circulation, organization, hierarchy, and concept as they relate to each other.  Partis are all about the interlocking relationships of parts of the design process.