The formal definition contains the following parts:
1. The term that names the thing or idea.
2. The class or category to which the term belongs (for instance, copper can be grouped with “metals”)
3. The characteristics of the term that set it apart from others in its class (for instance, a metal that is ductile, malleable, a good conductor, and whose atomic weight is 65.34)
4. Any common abbreviations or acronyms for the term (for instance, Cu)
These basic elements of a formal definition can be combined into a sentence or two. The following example has been numbered to show the four basic elements:
Example 1. A central processing unit  (CPU)  is a set of electronic components in a computer system  that controls the interpretation and execution of instructions.
Example 2. Evaporation  is a process in water cycle  where liquid changes to gas. 
“Creative Writing versus Technical Writing”
It is often difficult to distinguish the differences and similarities between Technical Writing and Creative Writing. Writing is writing and good writing is creative writing. If we accept, however, that Technical Writing exists in its own category, with Creative Writing in another, how can we categorize creative Technical writing? One way to explore the differences and similarities between Technical Writing and Creative Writing is to analyze them with regard to subject, purpose, audience and voice. Even a rudimentary analysis of these two writing styles in terms of subject, purpose, audience and voice will expose the fact that Creative Writing encompasses a broader scope of writing than Technical Writing, with fewer limitations.
The subject and purpose in Technical Writing and Creative Writing differ in that Technical Writing is always nonfiction, with the purpose of educating or instructing, while Creative Writing can be fiction, nonfiction, or a combination of both, and can serve any purpose. Creative Writing is nonrestrictive, encompassing goals from education to entertainment. In contrast, Technical Writing is never meant to entertain, though it can be entertaining at times, depending on the subject, purpose, and audience being addressed. Entertaining Technical Writing can be considered creative Technical Writing.
Creative Writing subjects can be fiction, nonfiction, or a combination of both, as is usually the case with biographies. Technical Writing focuses on nonfiction, technical procedures, methods, or processes. Creative Writing can be about any subject, from fantastical stories of Mickey Mouse to hard-boiled detective stories about corrupt policemen. Technical Writing about Mickey Mouse might include a user manual about a Mickey Mouse website, telephone or video game, or some back-end documentation about an interactive Mickey Mouse website.
Just as the subject of Technical Writing is limited to nonfiction, with the purpose of educating or instructing, the audience in Technical Writing is limited as well. The audience for Technical Writing can be divided into a technical and a non-technical audience, often defined by how this audience understands—or is trying to understand—the technical subject being presented in the writing. Test procedures, speculation documents, abstracts, flow charts and installation manuals usually address a technically proficient audience. User manuals, online help materials and abstracts address a semi-technical or non-technical audience.
In Creative Writing, audiences tend to be divided among age, hobby, taste, or interest. The audience that enjoys romance is addressed in Romance novels, while the...