“Gotta” is an informal spoken form of “got to,” often used to mean “have to” or “must.” It appears mostly in casual speech and dialogue, not in formal writing.
“Gotta” developed as “got to” was said quickly in everyday speech, causing the sounds to blend. Writers began spelling it this way to show natural conversation.
When you say “I gotta go,” you’re really saying “I have got to go,” which itself is just another way to say “I must go.” English stacks helping verbs like Lego pieces, then squashes them in speech.
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