A great challenge across business today is to achieve visibility into all the information produced within and outside the organization, fitting it to the context depending on the current scenario and for initiating effective action with the latest information. Information integration is one technique that helps in achieving this. Each organizations need for accessing information, list of input sources and in which form the outcome to be are all details contributing to the issues. Hence a need for a precise representation as to what information integration state is obvious. This paper gives the survey on various definitions stated for information integration which has been classified and discussed over the completeness of them analyzing on the three aspects input, output and process. Here the incompleteness of the stated definitions is explained in terms of where they limit. With these findings we present a comprehensive characterization of information integration with an effort to fit in all aspects i.e. meaning, distinctness and completeness of information integration leading to further research.