“Could” is a modal verb and the past form of “can,” but it is not limited to the past. It is also used for polite requests, possibility, permission, ability, and hypothetical situations.

1️⃣ Past Ability

Used to show ability in the past.

Structure:
Subject + could + base verb

Examples:

• I could swim when I was five.

• She could speak English fluently.

2️⃣ Polite Requests

Used to ask or request politely.

Structure:
Could + subject + base verb?

Examples:

• Could you help me, please?

• Could I borrow your pen?

3️⃣ Possibility

Used to express that something is possible or might happen.

Structure:
Subject + could + base verb

Examples:

• It could rain today.

• This news could be true.

4️⃣ Suggestions

Used to give light or polite suggestions.

Structure:
Subject + could + base verb

Examples:

• You could try calling him again.

• We could go out for dinner.

5️⃣ Permission

Used to ask for or give permission politely.

Examples:

• Could I leave early today?

• You could use my laptop if you want.

6️⃣ Unreal / Imaginary Situations

Used to talk about hypothetical or imaginary situations that are not real at present.

Examples:

• I could be a millionaire if I won the lottery.

• She could travel the world if she had more money.

✍️ Conclusion

“Could” is a versatile modal verb used for:

• Past ability

• Polite requests

• Possibility

• Permission

• Imaginary situations

Using “could” correctly makes your English more professional, polite, and fluent.