'can't' is a contraction of 'cannot.' It is a modal auxiliary verb used to express incapability, impossibility, or prohibition.
'can't' is used to indicate something that is not possible or is forbidden, express disbelief or skepticism about something, or denote an inability to do something.
I can't swim, so I'll stay by the shallow end of the pool.
You can't be serious! He really said that?
You can't park here; it's a no-parking zone.
'can't' is often used in spoken English and informal writing. In more formal contexts, 'cannot' might be preferred. Be cautious of the context
'can't' denotes a lack of ability, permission, or possibility, while 'can' indicates the opposite. A common mistake is confusing 'can't' with 'cant,' where the latter refers to insincere talk or jargon of a particular group. They have different meanings and usages. In some dialects or regional accents, the pronunciation of 'can't' might sound similar to 'can,' so it's essential to rely on context to determine the meaning.