XLS file extension stands for eXceL Spreadsheet and is the file format that holds the data in the Microsoft Excel worksheet. The Excel stores the data in rows and columns format and is enriched with the features such as; calculations, pivot tables, etc. Apart from these it displays charts, graphs, histograms, etc. the file .xls stores the information in a proprietary format, the format is BIFF (Binary Interchange File Format). The documents are stored in fixed-size streams and it contains all the meta-data related with it.