Microsoft Excel Spreadsheet (.xlsx)

XLSX is a file format used by Microsoft Excel for storing spreadsheet data. Introduced with the release of Excel 2007 as part of the Office Open XML standard, it is now the default format for creating spreadsheets using modern versions of Excel.

XLSX files are XML-based and have a more open structure than the older XLS format. This allows for smaller file sizes, better recovery of information from damaged files, and easier detection of files containing macros. XLSX files are supported by most spreadsheet applications and can be opened and edited on a variety of platforms.

Since its introduction, XLSX has become one of the most common file types for saving data in spreadsheets and is now typically referred to as just an Excel spreadsheet.