The fastercsv gem is a fast CSV parsing library. CSV—short for comma-separated values—is an unstandardized data-exchange format. Unlike XML—which has a formal standard and programs that can check a data file for validity—CSV has a great many different forms. However, CSV is also extremely easy to output, and quite common; for example, you can easily export and import CSV from desktop applications such as Microsoft Office or OpenOffice.org. Additionally, CSV is often used for business purposes, such as transferring millions of rows of inventory data.