This library generates diff reports of CSV files, using the diff capabilities of the CSV Diff gem. Unlike a standard diff that compares line by line, and is sensitive to the ordering of records, CSV-Diff identifies common lines by key field(s), and then compares the contents of the fields in each line. CSV-Diff Report takes the diff information calculated by CSV-Diff, and uses it to produce Excel, HTML, or text diff reports. It also provides a command-line tool (csvdiff) for generating these diff reports from CSV files. The csvdiff command-line tool supports both file and directory diffs. As directories may contain files of different formats, .csvdiff files can be used to match file names to file types, and specify the appropriate diff settings for each file type.