Business Processes are the life fluid of an Enterprise, moving and shifting to respond to ever changing business environment. They are sets of activities in an organization that are performed in response to a trigger — an external stimulus, an internal state change, a point in time is reached — to provide a desired result in response to that trigger.
The nature of business processes lends itself to diagramming them in some manner. You can present: the starting and end points as circles; all the Activities as boxes (rounded corners preferred); Decision Points as diamond shapes; arrowed lines connecting all of the above; swim-lanes optional. What all this drawing means is that, given sufficient effort, it is possible to fully define a process as it exists at a point in time.
Why the emphasis on a point in time? Consider how most business’ processes and activities were automated for the first time; the process was defined, and programmers design and code programs for a system that executes the activities. For the day this system is implemented, and for some period of time afterwards, the system does what it was designed to do, and the business performs its processes using that system. No one is aware that the business process is now frozen in time.
Fairly soon, however, the business decides to change its process somewhat to deal with new problems or opportunities; their system does not support this changed process, so a project is needed to open the system, make the changes (correctly), test the changes, and implement the new programs for the system. This takes time. The business process essentially must be thawed out, re-directed, and then re-frozen.