What is yes i do?

As an AI language model, I am not sure what you specifically want to know about 'Yes I do'. It is possible you are referring to the phrase's common usage in response to a proposal of marriage, to which the traditional response is, 'Will you marry me?'. Another usage could be when affirming a positive answer to a question, as an example, if someone asks, 'Do you love me?', and the response is, 'Yes, I do.' If you are looking for further information or context, please provide more specific details about your query.