What is Modal Verbs? Definition and Their Examples

When learning English grammar, one question often comes up: what is modal verbs? Modal verbs are a special type of auxiliary verb that help us express ability, possibility, necessity, or permission. For English learners, mastering modal auxiliary verbs is essential because they are used daily in both spoken and written English.

In this post, we’ll explore the definition, functions, and rules of modal verbs with plenty of modal verb examples to make everything clear. Whether you’re a beginner or looking to polish your grammar, this guide will give you the confidence to use modal verbs naturally.

What is Modal Verbs?

Modal verbs, also called modal auxiliary verbs, are verbs that work alongside the main verb in a sentence to change its meaning. They don’t show action by themselves but instead add a layer of meaning related to possibility, necessity, ability, or obligation.

Common modal verbs include:

• Can
• Could
• May
• Might
• Must
• Shall
• Should
• Will
• Would

Unlike normal verbs, modal verbs do not change form depending on the subject (for example, He can vs. They can—no -s is added).

Characteristics of Modal Auxiliary Verbs

Modal verbs are unique because they don’t follow the same rules as regular verbs in English. To master them, it’s important to understand these special characteristics:

1. No “-s” in the Third Person Singular

In English, most verbs take an -s ending when the subject is in the third person singular (he, she, it).

• Regular verb: She runs fast.
• Regular verb: He eats rice.

But modal verbs never take “-s” in the third person.

• ✅ She can drive.
• ❌ She cans drive.

This rule makes modal verbs easier to use than many other verbs, since you don’t have to worry about changing their forms depending on the subject.

2. Always Followed by the Base Form of the Verb

After a modal verb, we always use the base form (the infinitive without “to”).

• ✅ You must study hard.
• ❌ You must studies hard.

Another example:

• ✅ They will go tomorrow.
• ❌ They will goes tomorrow.

Even if the subject is singular, the verb remains in its base form when used with a modal auxiliary.

3. Express Shades of Meaning

One of the most important features of modal verbs is their ability to change the meaning of a sentence. The choice of a modal verb tells us about possibility, necessity, ability, or certainty.

For example:

• She can sing beautifully. (ability)
• You must wear a helmet. (necessity/obligation)
• They might arrive late. (possibility)
• He will pass the exam. (certainty about the future)

Notice how the meaning of the sentence depends on which modal verb we use. This flexibility allows speakers to express attitudes and emotions – not just actions.

4. Do Not Change with Tense (Mostly)

Unlike other verbs, modal verbs generally stay the same form regardless of tense.

• Present: I can swim.
• Past: I could swim when I was younger.

Some modals have past forms (can → could, will → would, shall → should), but they do not use endings like -ed or -ing.

5. No Infinitive or – ing Form

You cannot use modal verbs in the infinitive or continuous form. For example:

• ❌ To can, canning, musted
• ✅ Can, could, must

If you need to express similar meanings in different tenses, you use other verb structures like be able to instead of can.

Example:

• I will be able to drive next year. (future ability)

6. Used to Form Negatives Without “Do”

When making negatives, modal verbs don’t need the auxiliary verb do. You simply add not after the modal.

• ✅ You should not (shouldn’t) smoke here.
• ✅ He cannot (can’t) speak French.
• ❌ He doesn’t can speak French.

This makes sentences with modals simpler than those with normal verbs.

7. Used to Form Questions Without “Do”

Similarly, when asking questions, modal verbs come before the subject – no do is required.

• ✅ Can you help me?
• ✅ Should we start now?
• ❌ Do you can help me?

8. Politeness and Formality

Modal auxiliary verbs can also show the speaker’s tone – whether it’s polite, formal, or casual.

• Polite: Could you open the window, please?
• Formal: May I leave the room?
• Casual: Can I borrow your pen?

In short, modal auxiliary verbs are different from normal verbs in terms of form, usage, and meaning. They never change with subject, always use the base verb, and allow us to express subtle shades of meaning.

Functions of Modal Verbs

To truly understand what is modal verbs?, it helps to see how they are used in different contexts. Modal auxiliary verbs add special meanings to sentences. Let’s break them down by function, with multiple examples for each.

Ability

Can and could are commonly used to show ability.

• I can swim across the river.
• She can play the piano very well.
• They can solve this problem easily.
• When I was young, I could run very fast.
• He could read before he turned five.

Permission

Modal verbs like may and can are often used to give or ask for permission.

• You may leave early today.
• Can I borrow your book?
• Students may use the library after class.
• Can we sit here, or is it taken?
• You may enter the hall now.

Possibility

Might and Could show possibility, especially when we are not completely sure.

• It might rain this evening.
• This could be the answer we need.
• They might come to the party later.
• The results could change everything.
• She might be at the café right now.

Necessity or Obligation

Must and should show strong necessity, rules, or advice.

• You must wear a helmet.
• You should eat more vegetables.
• Passengers must fasten their seatbelts.
• Employees should respect the company rules.
• We must finish the project before Friday.

Future Intentions or Certainty

Will and Shall are used to express what will definitely or probably happen in the future.

• I will call you tomorrow.
• We shall overcome these difficulties.
• She will start her new job next week.
• They shall receive their certificates soon.
• This plan will save us a lot of time.

Hypothetical or Polite Expressions

Would is very useful for politeness and talking about imaginary or hypothetical situations.

• I would help you if I had the time.
• Would you like some coffee?
• If I were rich, I would travel the world.
• She would join us if she weren’t so busy.
• Would you mind opening the window?

With these examples, you can see how modal auxiliary verbs add different shades of meaning depending on the situation.

Modal Verb Examples in Sentences

Here are more examples to strengthen your understanding of modal auxiliary verbs:

1. She can speak three languages.
2. You must complete the homework before class.
3. They might visit us next week.
4. He should see a doctor about that cough.
5. We will celebrate your success tomorrow.
6. When I was a child, I could climb trees easily.
7. If I were you, I would take that opportunity.
8. She can drive a car without difficulty.
9. You may enter the room now.
10. It might snow later tonight.
11. We should leave early to avoid traffic.
12. He must wear glasses while reading.
13. They will join us for dinner.
14. I could hear a strange noise outside.
15. Can you help me with this exercise?
16. She may call you this evening.
17. You would enjoy this book—it’s very interesting.
18. We shall meet again soon.
19. He might be busy right now.
20. Students must follow the school rules.
21. I can cook Italian food.
22. She could dance beautifully when she was younger.
23. We should practice English every day.
24. He will arrive at the airport at 6 p.m.
25. If I had more time, I would learn Spanish.
26. Can I ask you a question?
27. You may use my laptop if you need it.
28. It could take hours to finish the project.
29. All passengers must show their tickets.
30. She should apologise for being late.

As you can see, each modal auxiliary verb changes the tone or meaning of the sentence – whether it’s ability, possibility, obligation, or politeness.

Modal Verbs in Questions

Modal verbs are also used to form questions:

• Can you play the guitar?
• May I join you?
• Should we start now?

They make questions sound polite and grammatically correct.

Common Mistakes with Modal Verbs

English learners sometimes make small but important errors. Here are a few to avoid:

• ❌ He cans play football.
• ✅ He can play football.
• ❌ You musts finish your work.
• ✅ You must finish your work.
• ❌ She can to sing well.
• ✅ She can sing well.

Remember: modal verbs are always followed by the base verb without “to” (except in some cases like ought to).

Why Are Modal Verbs Important?

Modal auxiliary verbs are everywhere in English communication. They allow us to express not only actions but also attitudes, possibilities, and levels of certainty. Without them, English would sound flat and unclear.

For example:

• I go tomorrow. (This sounds incomplete.)
• I will go tomorrow. (Now the meaning is clear—future intention.)

Understanding what is modal verbs? is not just about grammar – it’s about expressing yourself clearly and confidently.

Quick Modal Verb Chart:

Conclusion

So, what is modal verbs? They are auxiliary verbs that help us show ability, necessity, possibility, permission, and more. From simple sentences like I can swim to more complex expressions like I would have helped if I could, modal verbs give richness and accuracy to our communication.

By practising modal verb examples and noticing how native speakers use them, you’ll soon feel comfortable using modal auxiliary verbs in your own writing and conversations. Remember: small words like can, must, and should have big power in English!