You can use "ain't" in place of "am not" , "is not" "are not" or "have not". For example: I ain't (am not) doing that. You ain't (are not) going home. I ain't (have not) done that. He ain't (is not) right. It is, and I take this from one of our dictionaries, widely disapproved of and generally associated with the less educated. It would be better to use "am not", "is not", "are not" or "have not" when speaking. You will be understood if you say "ain't", however most people would probably recommend that you do not use it when talking to new people or when you are at work.

"ain't" is non-standard English and you would do best to avoid using it if your aim is to learn to write and speak the language in education, work and general social contexts in English-speaking countries.

Muchas gracias Scott. Tu español parece ser muy bueno!. La razón por la cual hice la pregunta fue que vi la palabra en muchas canciones, entonces me causo intriga. No tengo pensado usar la palabra mientras utilizo el idioma, pero no esta de mas saber su significado y como se usa. Nunca esta de mas saber.

Como la gente ha dicho, "ain't" no es inglés correcto. Debes decir "I am not", "You are not", o "It is not" pero nunca dice "I ain't" "You ain't" "It ain't." Saber "ain't" es importante, porque la gente en los EEUU lo dice a veces. (I am practicing my Spanish. I hope that was clear.) Use of the word "ain't" in spoken or written English is improper and is considered by some to be a sign of limited education. The only place "ain't" is considered acceptable (para mí) is in songwriting. Some popular songs (from my day): Ain't No Sunshine (When She's Gone) He Ain't Heavy (He's My Brother) Two Out of Three Ain't Bad Ain't No Stopping Us Now

It is an informal variant of "am not" and isn't considered "good English". You may hear it a lot because many native speakers use it, but definately avoid it as it isn't appropriate in many circumstances . Definately avoid it in writing.