Purpose is why we write. It is a rhetorical element of writing.
The basic purpose of all of our writing is to convey information to the reader and to persuade them. Throughout the semester’s assignments, we wrote for different purposes.
For example, in my memo assignment my purpose was to improve the environment in the campus restrooms and locker rooms of CCNY; in my technical description assignment my purpose was to show the reader a keyboard and persuade them why to choose this keyboard; in my lab report my purpose was to test the harm to people at different decibels (short-term) to reason about the harm to people exposed to noise for long periods of time; and the purpose of the group proposal was to design an application for early warning of natural disasters.