Abreviation of isn't it (Is it not)
"Innit" is put at the end of a question or statement meaning either:
- Do you agree?
- Are you following me/Do you understand?
"Innit has classically been added at the end of a sentence that contains the verb "to be", as "ISn't it" obviously refers back to a conjugation of the this verb. (See example 1.)
These days though, "innit" can be used eventhough the verb in the main sentence is not a form of "to be". (See example 2)
Example 1: That cake IS nice, innit?
Example 2: Cake GOES well with tea, innit?