OpenRefine is a tool for working with messy data that allows for data profiling, cleaning, extension, and ETL prototyping. The document outlines two use cases - cleaning inconsistencies in a city thesaurus XML file with over 5,000 concepts, and preparing city data for a contest by cleaning duplicates, adding new data from another project, and using the tool's project history. OpenRefine is a cross-platform web application that can be used as an intermediate step between systems for data manipulation and cleaning.