How to Correctly Use “That Is” in a Sentence (With Helpful Examples)

Navigating the nuances of English grammar can sometimes feel like a linguistic labyrinth, with common words and phrases often presenting unexpected challenges. Among these, the phrase “that is” frequently appears, prompting questions about its correct usage and purpose within a sentence.

Understanding how to employ “that is” effectively is crucial for clear communication, whether in formal writing or everyday conversation. It’s a versatile construction that, when used properly, can clarify meaning, introduce explanations, or emphasize a point. This article aims to demystify its application with detailed explanations and practical examples.

Clarifying Meaning and Definition

The most straightforward function of “that is” is to provide a definition or clarify the meaning of a preceding noun or concept.

This usage often serves to eliminate ambiguity, ensuring the reader or listener grasps the intended subject precisely.

It acts as a bridge, connecting a term to its explanation.

Introducing Explanations

When a sentence introduces a term and then immediately follows with an explanation or elaboration, “that is” is the perfect connector.

Consider a situation where you’ve mentioned a specific concept, and you want to ensure everyone understands what that concept entails.

This is where “that is” steps in to provide that much-needed clarification.

For instance, you might say, “We discussed ‘quantum entanglement,’ that is, the phenomenon where particles become linked and share the same fate, regardless of the distance separating them.”

Here, “that is” signals that the subsequent phrase will define or explain “quantum entanglement.”

Another example could be, “The team is working on the new ‘agile methodology,’ that is, an iterative approach to project management that emphasizes flexibility and customer collaboration.”

This structure ensures that even if the reader is unfamiliar with “agile methodology,” they receive a clear, concise definition.

The phrase functions similarly to introducing a synonym or a more descriptive phrase.

It’s a direct way to say, “What I mean by this is…”

The clarity provided by “that is” is invaluable in technical writing, academic papers, or any context where precision is paramount.

Synonymous Expressions

“That is” can often be replaced by or used interchangeably with phrases like “in other words,” “to wit,” or “namely,” though “that is” is generally more common in everyday English.

These alternatives serve a similar purpose: to rephrase or specify something mentioned previously.

Understanding these substitutions can further solidify your grasp of the phrase’s function.

For example, “He is a polymath, that is, a person of wide-ranging knowledge or learning.”

This could also be written as, “He is a polymath, in other words, a person of wide-ranging knowledge or learning.”

The core idea remains the same: providing a clearer or alternative phrasing of the preceding term.

The choice between “that is” and its synonyms often depends on the desired tone and formality of the writing.

“That is” is generally versatile and fits well in most contexts.

Emphasizing a Point

Beyond simple definition, “that is” can be employed to emphasize a specific aspect or a key takeaway from a statement.

It draws attention to a particular detail that the speaker or writer deems most important.

This usage adds weight and focus to the information that follows.

Highlighting Key Information

When you want to underscore a crucial detail or a specific conclusion, “that is” can serve as an effective tool.

It signals a shift in focus, directing the audience’s attention to what you consider the most significant part of your message.

Consider this: “The project was a success, that is, it met all its primary objectives within the allocated budget and timeline.”

Here, “that is” highlights the specific criteria that defined the project’s success, making it clear what aspects were most important.

Another instance might be: “Her primary concern is the safety of the community, that is, ensuring all residents feel secure in their homes and public spaces.”

This emphasizes the core of her concern by providing a concrete, explanatory elaboration.

The phrase acts as a spotlight, illuminating the specific element you wish to emphasize.

It’s a way of saying, “And this specific part is what truly matters.”

This technique is particularly useful in persuasive writing or when delivering a concluding statement that needs to leave a lasting impression.

It helps to crystallize the main point for the audience.

Adding Specificity

Sometimes, a general statement needs to be followed by a more specific detail to make it fully understandable or impactful.

“That is” facilitates this transition from general to specific.

It narrows the scope and provides concrete details.

For example, “The company is investing in new technology, that is, upgrading its entire server infrastructure to support advanced AI capabilities.”

This moves from a broad statement about investment to a specific example of that investment.

Another example: “He has a unique talent, that is, the ability to recall historical events with photographic accuracy.”

This clarifies what makes his talent “unique” by providing a precise description.

The phrase helps to ground abstract ideas in tangible examples.

It ensures that the audience has a clear, actionable understanding of the point being made.

This specificity prevents misinterpretation and enhances the overall clarity of the communication.

It’s about providing the essential details that flesh out a broader statement.

Distinguishing “That Is” from “That’s”

A common point of confusion arises between the full phrase “that is” and its contraction, “that’s.”

While related, their appropriate usage depends heavily on the context and desired level of formality.

Understanding this distinction is key to polished writing.

Contractions and Formality

“That’s” is a contraction of “that is” or “that has.”

In informal writing, such as personal emails, text messages, or casual blog posts, “that’s” is perfectly acceptable and often preferred for its conversational tone.

However, in formal academic papers, business reports, or official documents, it is generally best practice to use the full phrase “that is” to maintain a more professional and serious tone.

For instance, you might write in a text message, “That’s a great idea!”

But in a formal proposal, you would opt for, “That is an excellent suggestion.”

The choice between the two impacts the perceived formality of your writing.

It’s a subtle cue that signals the intended audience and purpose of your communication.

Being mindful of this distinction helps ensure your writing is appropriate for its context.

Using contractions in formal settings can sometimes be perceived as careless or unprofessional.

Avoiding Confusion with “That Has”

It’s important to remember that “that’s” can also stand for “that has.”

This dual nature can sometimes lead to ambiguity if not carefully managed.

Context is always the primary determinant.

If you write, “That’s been a long day,” “that’s” stands for “that has.”

If you write, “That’s the reason why,” “that’s” stands for “that is.”

When in doubt, especially in formal writing, expanding “that’s” to either “that is” or “that has” can prevent potential confusion.

This clarity is especially important in technical or legal documents where precision is critical.

The explicit use of “that is” leaves no room for misinterpretation regarding its grammatical function.

It unequivocally links a subject to its predicate or explanation.

“That Is” vs. “Which Is”

Another common grammatical hurdle involves distinguishing between “that is” and “which is.”

While both can introduce clauses, their grammatical roles and the types of clauses they introduce are distinct.

Understanding this difference is crucial for constructing grammatically sound sentences.

Restrictive vs. Non-restrictive Clauses

The core difference lies in the type of clause being introduced.

“That is” is typically used to introduce a restrictive clause, which is essential to the meaning of the sentence and provides identifying information.

Restrictive clauses are not set off by commas.

Conversely, “which is” is often used to introduce a non-restrictive clause, which provides additional, non-essential information about a noun and is set off by commas.

For example, “The car that is parked illegally will be towed.”

Here, “that is parked illegally” is a restrictive clause specifying which car will be towed. Removing it would change the meaning of the sentence.

Now consider: “My car, which is parked illegally, will be towed.”

In this case, “which is parked illegally” is a non-restrictive clause. It adds extra information about “my car” but isn’t essential to identify it. The sentence would still make sense as “My car will be towed.”

The presence or absence of commas is a strong indicator of which construction to use.

A restrictive clause, introduced by “that,” is vital to the sentence’s core meaning.

A non-restrictive clause, often introduced by “which,” offers supplementary detail.

This grammatical distinction ensures that the reader understands whether the information is critical or supplementary.

Omission of “Is”

In many cases, the word “is” can be omitted from the “which is” construction when introducing a non-restrictive clause, creating a more concise sentence.

This is a stylistic choice that often enhances flow and readability.

For example, “The book, which is on the table, belongs to Sarah.”

This can be shortened to, “The book, on the table, belongs to Sarah.”

The meaning remains clear, and the sentence becomes more streamlined.

However, “that is” typically requires the “is” to remain; omitting it would change the grammatical structure and meaning.

You cannot say, “The car that parked illegally will be towed.”

The “is” in “that is” is crucial for connecting the subject to its defining characteristic in restrictive clauses.

Mastering this “that” vs. “which” distinction, and understanding the role of “is” in each, is a hallmark of sophisticated sentence construction.

It allows for precise control over the emphasis and essentiality of information within your writing.

Using “That Is” for Transitions

The phrase “that is” can also serve as a useful transitional element, bridging different ideas or clauses within a sentence or paragraph.

It provides a smooth, logical connection between thoughts.

This transitional function helps guide the reader through complex arguments or narratives.

Connecting Related Ideas

When two ideas are closely related, with the second idea elaborating on or clarifying the first, “that is” can effectively link them.

It signals to the reader that the upcoming information is a direct continuation or explanation of what was just stated.

Consider: “The company is undergoing a major restructuring, that is, a complete overhaul of its organizational hierarchy and operational procedures.”

Here, “that is” connects the general concept of restructuring to its specific implications.

Another example: “He possesses a rare gift for empathy, that is, the ability to deeply understand and share the feelings of others.”

This links the abstract idea of a “gift” to its concrete manifestation in empathetic understanding.

The phrase acts as a logical connector, ensuring that related thoughts flow seamlessly.

It helps to build a coherent and well-supported argument or description.

This transitional role is vital for maintaining clarity, especially in longer or more complex pieces of writing.

It prevents ideas from seeming disconnected or abrupt.

Introducing Examples or Illustrations

While not its primary function, “that is” can sometimes be used to introduce an example, particularly when the example serves to define or illustrate a preceding statement.

This usage often overlaps with its role in clarification.

The example provided is meant to be a definitive illustration.

For instance: “The team needs to adopt a more proactive approach, that is, anticipating potential issues before they arise rather than reacting to them.”

In this sentence, the specific action of “anticipating potential issues” serves as a clear example of what a “proactive approach” entails.

Another instance might be: “We are focusing on core competencies, that is, developing our strengths in software engineering and data analysis.”

This clarifies the general focus by providing specific areas of expertise.

While phrases like “for example” or “such as” are more common for introducing examples, “that is” can be used when the example is intended as a direct clarification or definition of the preceding term.

It’s about providing the quintessential example that embodies the concept.

This usage ensures that the illustration is not just supplementary but integral to understanding the initial statement.

The example becomes a definitive representation of the idea.

Common Pitfalls and How to Avoid Them

Despite its utility, “that is” can be misused, leading to awkward phrasing or grammatical errors.

Awareness of these common pitfalls is the first step toward avoiding them.

By understanding typical mistakes, writers can refine their use of this phrase.

Overuse and Redundancy

One common issue is the overuse of “that is,” leading to sentences that sound repetitive or wordy.

If a sentence already clearly defines or explains a term, adding “that is” can be redundant.

For example, “The term ‘onomatopoeia,’ that is, a word that imitates a sound, is often used in children’s literature.”

This sentence is redundant because the phrase “a word that imitates a sound” already defines “onomatopoeia.”

A more concise version would be: “The term ‘onomatopoeia,’ a word that imitates a sound, is often used in children’s literature.”

Or even simpler: “Onomatopoeia, a word that imitates a sound, is often used in children’s literature.”

Always ask yourself if the explanation following “that is” is truly necessary or if the meaning is already clear.

Conciseness is key to effective writing.

Eliminating unnecessary words makes your prose stronger and more direct.

Read your sentences aloud to catch awkward or redundant phrasing.

Incorrect Placement of Commas

Mistakes in comma usage around “that is” can alter the intended meaning, particularly when it comes to distinguishing between restrictive and non-restrictive clauses.

As previously discussed, restrictive clauses essential for meaning do not use commas, while non-restrictive clauses do.

Consider the difference: “The report that is due tomorrow needs final approval.”

This sentence implies there are multiple reports, and the one that is due tomorrow is the one needing approval (restrictive, no commas).

Now consider: “The report, that is, the final draft, needs final approval.”

This sentence structure is generally incorrect. If “the final draft” is meant to explain “the report,” it should be set off by commas as a non-restrictive appositive, but “that is” is typically not used this way with commas.

A better construction would be: “The report, the final draft, needs final approval.”

Or, if the “is” is crucial: “The report, which is the final draft, needs final approval.”

Remember that “that is” introduces defining information and generally avoids commas unless part of a larger parenthetical structure that isn’t the primary function of “that is” itself.

Proper comma placement ensures the reader understands whether the information is essential or supplementary.

It’s a subtle but significant aspect of clear sentence structure.

When in doubt, consider if the clause modifies the noun directly and essentially, or if it provides extra, non-essential detail.

Confusing “That is” with “That”

Sometimes, writers include “that is” unnecessarily when a simple “that” would suffice.

This often happens when “that” is used as a relative pronoun introducing a restrictive clause.

The addition of “is” is grammatically incorrect in such cases.

For example, “This is the book that is on the top shelf.”

This sentence is redundant. The “is” is unnecessary because “that” already functions as the relative pronoun connecting “book” to its location.

The correct sentence is: “This is the book that on the top shelf.”

Wait, that’s incorrect. The correct sentence is: “This is the book that is on the top shelf.”

Let’s rephrase: A more accurate example of unnecessary inclusion would be: “She is the person that is responsible for the project.”

This can be more concisely written as: “She is the person responsible for the project.”

Or, if the verb is needed: “She is the person who is responsible for the project.”

The key is to recognize when “that” alone adequately introduces the relative clause without needing the additional “is.”

This refinement leads to more economical and elegant prose.

It’s about ensuring every word serves a distinct grammatical purpose.

Avoid adding “is” simply because it feels like something should follow “that.”

Advanced Usage and Stylistic Choices

Beyond its fundamental roles, “that is” can be employed with more nuanced stylistic intentions.

These advanced uses can add sophistication and precision to one’s writing.

Exploring these techniques allows for a deeper mastery of the phrase.

Using “i.e.” vs. “e.g.” Equivalents

While not a direct replacement, the function of “that is” often aligns with the clarifying purpose of “i.e.” (id est, meaning “that is”).

However, “that is” is a complete English phrase, whereas “i.e.” is an abbreviation derived from Latin.

In formal writing, using “that is” can sometimes be preferred over “i.e.” for its directness and avoidance of potential confusion for readers unfamiliar with Latin abbreviations.

For example, instead of “The event is for advanced practitioners, i.e., those with at least five years of experience,” one could write, “The event is for advanced practitioners, that is, those with at least five years of experience.”

Both convey the same meaning of clarification.

The choice often depends on the target audience and the desired level of formality.

It’s important not to confuse this with “e.g.” (exempli gratia, meaning “for example”), which introduces examples rather than equivalent definitions.

“That is” is about equivalence or exact clarification, not exemplification.

Using “that is” when “e.g.” is appropriate would be a semantic error.

For instance, writing “We need to buy fruit, that is, apples, bananas, and oranges” is incorrect; it should be “We need to buy fruit, e.g., apples, bananas, and oranges.”

The phrase “that is” is best reserved for defining or rephrasing.

Strategic Pauses and Emphasis

In spoken language, the phrase “that is” can create a deliberate pause, signaling to the listener that important clarifying information is forthcoming.

This pause can add dramatic effect or simply ensure that the listener is prepared to receive the explanation.

Writers can sometimes mimic this effect through punctuation or sentence structure.

For example, a writer might use an em dash for a similar effect: “He was facing a dilemma—a choice between his career and his family.”

While “that is” isn’t explicitly used, the em dash serves a parallel function of introducing a clarifying statement.

In writing, the phrase itself, when used thoughtfully, can create a momentary pause in the reader’s mind, drawing attention to the subsequent clarification.

It’s a way of controlling the rhythm and pacing of the text.

This deliberate use can enhance the impact of the explanatory phrase that follows.

It encourages the reader to slow down and absorb the critical information.

This stylistic choice can make writing more engaging and impactful.

It’s about guiding the reader’s comprehension pace.

Conclusion

Mastering “that is” involves understanding its core functions: defining, clarifying, and emphasizing.

By distinguishing it from its contraction “that’s” and its counterpart “which is,” and by avoiding common pitfalls like overuse and incorrect punctuation, writers can wield this phrase with confidence.

Its correct application significantly contributes to clear, precise, and effective communication.