Writing Technical Descriptions

A technical description explains in clear, detailed terms what something is, what it looks like, or how it works. Its purpose is to give readers an accurate understanding of a product, mechanism, or process so that they can use it, build it, repair it, or simply understand it.

Writing mechanism and process descriptions is a critical skill for both engineers and computer scientists. Mechanism descriptions help clients determine whether a mechanism meets their needs, assist technicians in understanding how objects are assembled and function, and allow designers to document the development of new technologies. Process descriptions, on the other hand, explain how natural or technological processes work, such as how a quantum computer performs calculations.

Descriptions should be tailored to meet the specific needs of the audience. In other words, the focus and level of detail in a description should be adjusted based on what the reader will do with the information. A lay reader may need only a general understanding of how a particular device or system works, whereas a technician might require much greater detail.

Regardless of the level of detail required, when you describe an object, system, or process, aim to create a clear picture with words. As you do this, address key questions that help your reader understand what you’re describing:

• What is it?
• What does it do?
• What does it look like, or what are its stages?
• What is it made of, or what elements or factors are involved?
• How does it work or function?
• How is it put together or organized?

Impartiality in Technical Descriptions

Technical descriptions should provide an impartial view, meaning that they focus on observable details and avoid personal impressions or subjective language. Consider the following two samples, one subjective and one objective:

The subjective description uses adjectives like fantastic or outstanding which convey emotional responses rather than facts. In contrast, the objective description provides specific, observable details, such as measures 7.6 cm in diameter or a mass of 450 grams. When writing technical descriptions, avoid subjective or emotional language. Focus instead on precise, concrete details that allow readers to form their own conclusions.

Precision in Technical Descriptions

Precision refers to the use of specific terminology, exact measurements, and carefully defined parameters that eliminate ambiguity. Precision is a key virtue in technical descriptions because it ensures reproducibility, allows for accurate comparisons, and enables readers to make informed decisions based on factual data rather than approximations or generalizations. For instance, instead of saying The motor is small and quiet specify as The motor measures 7.6 cm in diameter, weighs 450 grams, and produces 42 dB of sound when measured from a distance of 1 m. Providing such precise details ensures clarity and helps your audience visualize the object or system more effectively. However, include only as much detail as your audience needs.

Organization of Mechanism and Process Descriptions

While impartiality and precision are essential in all technical descriptions, the way information is organized differs between mechanism and process descriptions.

Writing Mechanism Descriptions

Think of a mechanism description as a precise visual portrayal. These descriptions typically focus on tools or systems composed of multiple parts that work together to perform a specific function. The text in the description focuses on physical characteristics. It may include details such as size, shape, color, finish, fit, and other attributes, both for the mechanism as a whole and for each of its parts.

Visual elements, such as figures, diagrams, and images, should be closely integrated with the text. In other words, the text should directly reference the visuals, while the visuals should reinforce or expand upon the information provided in the text.

Structuring Mechanism Descriptions

When writing a mechanism description, it is essential to use a clear and logical structure. This typically begins with the overall function and composition of the mechanism, followed by a breakdown into its individual components. For instance, in describing an internal combustion engine, you would first present an overview of its structure and purpose before detailing its subcomponents, such as the cylinder head, engine block, and pistons. A key principle is to start with the larger picture in an introduction—giving readers a cognitive framework to connect with more specific details. Once the overall purpose and function is established, the description should proceed in a systematic order. Fig. 9.1 shows how you can structure a mechanism description to help the reader easily understand the mechanism of an object or system.

Fig. 9.1 Key elements of a mechanism description.

The Introduction

As with other forms of writing, you’ll likely begin with an introduction. This introduction may start with a basic definition, which is then expanded. You should first describe the mechanism’s overall function and purpose. You can also mention its general appearance, including its shape, size, color, material, finish, or texture. Importantly, you should list the mechanism’s parts in the order in which they will be described in your document.

The introduction to a mechanism description is essential for providing context and a broad overview, helping readers navigate the subsequent details. You can include the following elements to prepare the reader for what follows:

• A technical definition of the mechanism
• An extension of the definition, incorporating key theory or principles as background (only if necessary for the reader)
• A statement of overall function and purpose of the mechanism
• A description of the mechanism’s overall appearance, including relevant attributes such as shape, color, material, finish, texture, mass, weight, or size
• A list of components in the order they will be described

Writing Definitions

You may need to provide definitions whenever readers don’t share the same level of expertise in the domain. Therefore, technical descriptions typically begin with a clear definition of the mechanism or system. Here, it’s important to distinguish between two types of definitions: basic definitions and extended definitions.

Basic Definitions

A sentence providing a basic definition typically consists of the following key elements:

• The term being defined—the word or concept to explain
• The category or class—the broader group to which the term belongs
• Distinguishing details—additional characteristics that distinguish the term from others in its category

For example, consider the term thermal expansion valve. A basic definition of the term could be as follows:

Tips for Basic Definitions

The following techniques may help you make definitions precise and reader-friendly:

• Avoid circular definitions. In other words, do not use the word you are defining in its own definition.

This definition is circular because it uses the term aileron to define itself, which gives no useful information about the category or class of mechanisms to which the aileron actually belongs.

This definition avoids using the term in its own explanation and clearly describes what an aileron is and how it functions.

• Keep basic definitions concise and clear.

This definition is vague, wordy, and filled with generalizations that fail to clearly explain what a turbofan engine is or how it works.

This definition is concise, clearly states which category the item belongs to, and provides just enough distinguishing detail to understand its basic function without overwhelming the reader.

• Ensure precision. Definitions should be accurate and specific to avoid ambiguity.

This definition lacks specificity about the type of metal, how it’s shaped, and exactly how it reinforces concrete.

This definition specifies the material, form, placement, and purpose clearly.

• Know your audience. For readers with technical expertise, include only essential definitions. For readers with less expertise, explain technical terms or highlight them in bold or italics and refer readers to a glossary.
• Consider placement. Short definitions can be embedded directly within the text so that they don’t disrupt the flow of ideas. Longer definitions could be placed in a glossary or appendix.

By carefully crafting basic and extended definitions, you make your technical reports clearer and more accessible to a diverse audience.

Extended Definitions

Extended definitions begin with a basic definition but provide additional details, such as

• History—the origin and development of the term
• Etymology—the linguistic roots of the term
• Applications—how a technology is used
• Operation—how a process, technology, or system works
• Components—the parts that make up a technology

An extended definition for thermal expansion valve focusing on the history of its development could be as follows:

Outlining Overall Function and Purpose

In the introduction, it’s helpful to clearly state the overall function and purpose of the mechanism. This helps readers understand what the mechanism does before getting into the specific components and how they work. Consider the following example:

This sentence explains what the system does and why it is useful, giving readers a clear sense of its overall purpose. With that framework in mind, they can more easily see how each component contributes to the whole. This top-down approach makes the description clearer and easier to follow.

Outlining Structural Breakdown

After establishing a mechanism’s overall purpose and function, the next step is to provide a clear overview of its physical breakdown. This gives readers a mental image of the complete system and creates a framework for understanding how the individual components fit into the whole. When outlining the overall make-up, you should carefully consider the sequence in which the parts are introduced.

Part-By-Part Description

Following the introduction, the next step is to discuss the individual components. Precise description of each component is crucial for design, safety, verification, and standardization.

For each component, include the following:

• A definition of the component, with theory or operating principles as needed
• A description of its function and purpose within the mechanism
• A detailed description of properties (shape, color, material, finish, texture, size, etc.) that relate directly to its purpose and function
• Figures, diagrams, or photographs, as necessary (Ensure visuals do not overwhelm or distract the reader.)
• A transition to the next component in the description

Repeat this pattern for each subsequent component.

In choosing which features to describe, the key is relevance—include only the features that help readers visualize the part and, more importantly, reinforce the broader claims about function and purpose established in the introduction. For example, if a key feature of a tool is its strength and durability, it would be important to discuss its materials and their ability to resist forces without cracking or deforming. On the other hand, if you are describing a system designed to transmit information efficiently across a network, you would focus on characteristics related to that function. In short, you must be selective in what you choose to describe and ensure that every detail serves a clear purpose.

The Conclusion

Your mechanism description should also have a brief conclusion. This should summarize key points and reiterate essential information from the introduction.

• Summarize the overall function purpose of the mechanism.
• Optionally, provide a brief overview of one full operating cycle of the mechanism.

Visuals

Visual aids are nearly always essential in mechanism descriptions and should be closely integrated with the text. Your writing should refer directly to each visual, and the visuals should reinforce or expand upon the information presented. Include only those that enhance understanding—never use them as mere decoration. When using multiple visuals, number them and refer to them in sequence.

Writing Process Descriptions

Writing a process description is similar to writing a mechanism description, but with a different focus. While mechanism descriptions explain how something is built or how its parts fit together, process descriptions focus on a sequence of actions that lead to a specific result. Take ChatGPT as an example. A mechanism description might explain its architecture like neural network layers or attention mechanisms. A process description, on the other hand, would walk through the steps it takes to generate a response, from receiving the input to producing the output.

Structuring Process Descriptions

When writing a process description, use a clear structure that guides readers step by step. This typically involves following a chronological or cause-and-effect sequence. Begin with an overview of the entire process to give readers a framework for connecting the detailed stages that follow. Then move through each step in order, showing how one leads logically to the next. This creates a flow that mirrors how processes unfold in real-world applications, making transitions easy to follow. Figure 9.2 illustrates how to structure a process description so readers can track the sequence of actions, understand their purpose, and see how they work together to support the system’s overall function.

Fig. 9.2 Key elements of a process description.

Introduction

Similar to the mechanism description, a process description typically begins with an introduction. This gives readers the big picture before they get into the specific steps of the process. Start with a definition of the process, along with an overview of its core functions and purpose. Then, outline the main phases in the order in which they are described in the step-by-step description. The introduction includes the following:

• A technical definition of the process
• An extension of the definition, incorporating key theory or principles as background (only if necessary for the reader)
• A statement of overall function and purpose of the process
• A description of overall flow of the process
• A list of phases in the order they are described

Step-By-Step Description

After the introduction, break the process down into steps or phases and describe them one at a time, in the order they occur. This section walks the reader through each step or phase, showing how the whole process proceeds from start to finish. Each phase description should be well-structured and organized. Start with a basic definition of the phase, then mention its function and purpose within the overall process. Next, provide details of the specific activities, transformations, or operations that occur during the phase. Focus on what is relevant and only include details that help readers understand the phase’s role in the overall process and support the broader claims made in the introduction. For instance, if a key feature of a phase is data transformation, emphasize how the input information is processed and changed during this stage. If you’re describing a phase designed to analyze patterns, focus on the analytical methods and their significance to the overall process outcome. The final part of each phase description may include a transition to the next phase. Explain how the output of the current phase serves as the input for the next phase. This highlights the sequential nature of the process. Repeat this pattern for each phase until you have described the complete process from start to finish.

For each step/phase, include:

• A technical description of the step/phase, explaining what it does, how it works, and why it is necessary.
• A description of its function and purpose within the overall process.
• A detailed explanation of what occurs during the step/phase and how it happens.
• A description of the step/phase‘s output or result.
• Figures, diagrams, or photographs, as necessary (Ensure visuals do not overwhelm or distract the reader.)
• A transition to the next step/phase in the process sequence.

Repeat this pattern for each subsequent step/phase of the process.

Conclusion

Your process description should conclude with a concise summary. This section brings together the main ideas and emphasizes the most important details from previous sections.

• Summarize the overall function of the process.
• Re-list the steps/phases described.
• Optionally, provide a brief overview of one full operating cycle of the process.