A modal verb is a type of auxiliary verb used to express ability, possibility, necessity, permission, or obligation. Modal verbs modify the meaning of the main verb in a sentence and include words like:

• Can (ability, permission) – She can swim.
• Could (past ability, possibility) – He could read when he was three.
• May (permission, possibility) – May I use your phone?
• Might (possibility) – It might rain later.
• Must (necessity, strong recommendation) – You must wear a seatbelt.
• Shall (offers, suggestions) – Shall we dance?
• Should (advice, obligation) – You should see a doctor.
• Will (future intention, willingness) – I will call you tomorrow.
• Would (polite requests, hypothetical situations) – Would you like some tea?