Know, Knew, Known: What Is the Difference? Meaning, Grammar,

Understanding the difference between know, knew, and known is essential for speaking and writing English correctly. These three words are forms of the same irregular verb, know, which means to have information, understand something, or be familiar with a person or place. Although they share the same basic meaning, they are used in different grammatical situations.

The main difference is that know is the base form and present-tense form, knew is the simple past tense, and known is the past participle. For example, you might say, “I know the answer” when you understand something now, “I knew the answer yesterday” when referring to the past, and “I have known her for years” when describing something that began in the past and continues into the present.

Learning these forms will help you avoid common grammar mistakes and make your English sound more natural. In this guide, you will discover their meanings, grammatical rules, differences, and practical examples.

Quick Answer: Know vs. Knew vs. Known

Know, knew, and known are three forms of the irregular verb know. Use know for the present or base form, knew for the simple past, and known with helping verbs such as have, has, and had. For example: “I know him,” “I knew him,” and “I have known him for years.”

Why Do People Confuse Know, Knew, and Known?

People often confuse these words because they all come from the same verb and describe knowledge, awareness, or familiarity. Their meanings are closely related, but their grammatical functions are different.

The verb know is irregular, so it does not form its past tense by simply adding -ed. Instead, its three principal forms are:

• Know: Base form and present tense.
• Knew: Simple past tense.
• Known: Past participle.

The most common mistake is using knew after have or has. For example, “I have knew him for years” is incorrect. The correct sentence is “I have known him for years.”

Remembering which helping verbs work with each form makes the difference much easier to understand.

First Word: Know

Know is the base form of the verb and is used to describe having information, understanding something, or being familiar with someone or something.

Meaning of Know

The word know can express several related ideas:

• Have information: I know the answer.
• Understand: I know what you mean.
• Be familiar with someone: I know your brother.
• Recognize or be aware of something: I know that sound.

When Should You Use Know?

Use know when talking about the present, after modal verbs, and in certain sentence structures that require the base form.

Examples:

1. I know the way to the station.
2. They know how to solve this problem.
3. We know the truth.
4. You should know the rules.
5. I want to know your opinion.

Notice that know becomes knows with third-person singular subjects in the simple present tense.

• I know the answer.
• She knows the answer.
• They know the answer.

Second Word: Knew

Knew is the simple past tense of know. It describes information, understanding, or familiarity that existed at a particular time in the past.

Meaning of Knew

Use knew when referring to something a person understood, was aware of, or was familiar with in the past.

Examples:

• I knew the answer during the test.
• She knew about the meeting yesterday.
• We knew each other in school.
• He knew that something was wrong.

When Should You Use Knew?

Use knew in simple past sentences, often with expressions such as yesterday, last year, at that time, and when I was younger.

Examples:

1. I knew him when we were children.
2. She knew the answer before the teacher explained it.
3. They knew about the changes last week.
4. He knew where to find the keys.
5. We knew the journey would be difficult.

Important grammar rule: Do not use knew directly after have, has, or had in standard English. Use known instead.

Incorrect: I have knew her for ten years.

Correct: I have known her for ten years.

Third Word: Known

Known is the past participle of know. It is generally used with helping verbs to form perfect tenses and in passive constructions.

Meaning of Known

The word known expresses knowledge or familiarity in grammatical structures that require a past participle.

Examples:

• I have known him for years.
• She has known the truth since Monday.
• They had known each other before the event.
• He is known for his honesty.

When Should You Use Known?

Use known in the following situations.

1. Present perfect tense

Use have/has + known to describe knowledge or familiarity that started in the past and may continue into the present.

• I have known her since childhood.
• He has known the answer for a long time.

2. Past perfect tense

Use had + known for something that was already known before another past event.

• I had known about the problem before the announcement.
• She had known him for years before they worked together.

3. Passive constructions and descriptions

Use known in expressions such as is known as, was known for, and is well known.

• The author is known for her novels.
• This place is known as a historic landmark.
• He was known for his kindness.

Know vs. Knew vs. Known: Comparison Table

Word	Grammatical form	Main use	Example
Know	Base form / present	Present knowledge or familiarity	I know the answer.
Knows	Third-person singular present	Present knowledge with he, she, or it	She knows the answer.
Knew	Simple past	Knowledge in the past	I knew the answer yesterday.
Known	Past participle	Perfect tenses and passive constructions	I have known her for years.
Knowing	-ing form	Continuous, participial, or gerund constructions where appropriate	Knowing the truth helped me.

The three main forms to remember are know – knew – known. The other forms follow their own grammatical patterns.

When to Use Know, Knew, and Known

Choosing the correct form depends on the time and sentence structure.

Use Know for the Present or Base Form

Use know when the information is current or when a sentence requires the base form.

• I know his name.
• Do you know the answer?
• You must know the facts.
• They want to know more.

Use Knew for the Simple Past

Use knew when describing knowledge or familiarity at a past time.

• I knew the answer yesterday.
• She knew him in college.
• We knew it was going to rain.

Use Known After Have, Has, or Had

Use known with these helping verbs to form perfect tenses.

• I have known him since 2020.
• She has known about it for months.
• They had known each other before the trip.

Use Known in Expressions of Reputation

Use known in descriptions of how a person or place is recognized.

• She is known for her excellent work.
• The town is known for its beautiful scenery.
• He became known as a talented musician.

15 Examples of Know, Knew, and Known in Sentences

Here are 15 practical examples to help you understand how each form works.

Examples With Know

1. I know the correct answer.
2. Do you know where my phone is?
3. They know how to play chess.
4. We know that practice improves our skills.
5. You should know the importance of honesty.

Examples With Knew

6. I knew the answer before the teacher asked.
7. She knew about the surprise party.
8. He knew the road was dangerous.
9. We knew each other when we were young.
10. They knew that the decision was important.

Examples With Known

11. I have known my best friend for twelve years.
12. She has known the truth since yesterday.
13. They had known about the changes before the meeting.
14. The singer is known for her powerful voice.
15. He is well known in his community.

These examples show that the correct form depends on the sentence’s tense and grammatical structure, not simply on the meaning of the verb.

Common Mistakes With Know, Knew, and Known

Even experienced English learners sometimes mix up these forms. The following mistakes are especially common.

Mistake 1: Using Knew After Have

Incorrect: I have knew him for a long time.

Correct: I have known him for a long time.

Why? The present perfect tense requires have/has + past participle.

Mistake 2: Using Known as the Simple Past

Incorrect: I known the answer yesterday.

Correct: I knew the answer yesterday.

Why? The simple past form is knew. The word known usually needs a helping verb in these constructions.

Mistake 3: Using Know Instead of Knows

Incorrect: She know the truth.

Correct: She knows the truth.

Why? In the simple present tense, use knows with he, she, and it, as well as singular nouns.

Mistake 4: Using Knew After Did

Incorrect: Did you knew about the meeting?

Correct: Did you know about the meeting?

Why? After did, use the base form of the verb.

Mistake 5: Confusing Past and Present Perfect

Incorrect: I have knew her since childhood.

Correct: I have known her since childhood.

Why? The present perfect often describes a situation that began in the past and continues now. The correct form is have known.

Memory Trick: How to Remember Know, Knew, and Known

A simple way to remember the three forms is to connect each one with a familiar time or helping verb.

• Know = Now: I know the answer now.
• Knew = Past: I knew the answer yesterday.
• Known = Have, Has, or Had: I have known the answer for years.

Remember this pattern:

Know → Knew → Known

Say the three forms aloud a few times, then make your own sentence with each word. Practicing them together helps you remember their different grammatical roles.

Know, Knew, and Known in American vs. British English

There is no difference between American and British English in the standard forms of this verb.

Both varieties use:

• Know as the base form and present-tense form.
• Knew as the simple past tense.
• Known as the past participle.

Examples in American English:

• I knew the answer.
• I have known him for years.

Examples in British English:

• I knew the answer.
• I have known him for years.

The spelling and principal verb forms remain the same in both varieties. You should use the form required by the sentence’s grammar regardless of whether you are writing American or British English.

Similar Words and Related Verb Forms

Understanding related forms can help you improve your grammar and vocabulary.

Word	Meaning or function	Example
Knows	Present tense with a third-person singular subject	He knows the answer.
Knowing	-ing form of the verb	Knowing the rules is helpful.
Knowledge	Noun meaning information or understanding	Her knowledge of history is impressive.
Aware	Adjective meaning informed or conscious	She is aware of the problem.
Recognize	Identify someone or something familiar	I recognize his voice.
Understand	Grasp the meaning of something	I understand your question.

Although aware, recognize, and understand are related in meaning, they are not interchangeable with know in every sentence.

For example, “I know the answer” and “I understand the answer” may both be correct, but they can emphasize different aspects of having information or comprehending it.

Final Verdict: Know, Knew, or Known?

The correct choice depends on the tense and structure of your sentence.

• Use know for the base form and present knowledge: “I know the answer.”
• Use knew for knowledge in the simple past: “I knew the answer yesterday.”
• Use known as the past participle: “I have known the answer for years.”

The most important rule is to use knew for the simple past and known after have, has, or had in perfect-tense constructions. Remember these three forms, and you will be able to use this common irregular verb with greater confidence.

FAQs:

1. What are the three forms of know?

The three principal forms are know – knew – known. Know is the base form, knew is the simple past tense, and known is the past participle.

2. Is knew the past tense of know?

Yes. Knew is the simple past tense of know. For example, “I know the answer today” becomes “I knew the answer yesterday.”

3. Is it have knew or have known?

The correct form is have known. The present perfect tense uses have or has followed by the past participle. For example, “I have known her for years.”

4. Is known a past tense or a past participle?

Known is the past participle of know, not its simple past tense. It is used in perfect tenses, such as “She has known him for years,” and in passive or descriptive constructions, such as “He is known for his work.”

5. Which is correct: I knew him or I have known him?

Both are correct, but they are used differently. “I knew him” describes familiarity in the past without necessarily connecting it to the present. “I have known him” often describes familiarity that began in the past and continues now, depending on the context.

6. What is the past participle of know?

The past participle is known. It appears in sentences such as “I have known the answer for a long time” and “She had known him before the event.”

7. Is know an irregular verb?

Yes. Know is an irregular verb because its past tense and past participle do not follow the regular -ed pattern. Its principal forms are know, knew, and known.

Remember This

• Know = base form or present knowledge.
• Knew = simple past tense.
• Known = past participle.
• Use knows with he, she, or it in the simple present.
• Use did + know, not did + knew.
• Use have/has/had + known in perfect-tense constructions.

Conclusion

The difference between know, knew, and known becomes simple once you understand their grammatical roles. Know refers to the base form or present knowledge, knew describes knowledge in the simple past, and known is the past participle used with helping verbs and in certain descriptive constructions. Although these words share the same basic meaning, they cannot be substituted for one another in every sentence.

To improve your English, practice using all three forms in everyday situations. Say, “I know the answer,” “I knew the answer yesterday,” and “I have known the answer for years.” These simple examples demonstrate how the verb changes according to the sentence structure. With regular practice, you will make fewer grammar mistakes and communicate your ideas more clearly and confidently.