A file with the .xlsx file extension is a Microsoft Excel Open XML Spreadsheet (XLSX) file created by Microsoft Excel. You can also open this format in other spreadsheet apps, such as Apple Numbers, Google Docs, and OpenOffice. They are stored as a compressed Zip file, which contains a bunch of other files used to open the document.

RELATED: What Is A File Extension?

What Is an XLSX File?

XLSX files are files used in Microsoft Excel, a spreadsheet application that uses tables to organize, analyze, and store data. Each cell can contain text or numerical data, including incorporating mathematical formulas.

First introduced with Microsoft Office 2007 in the Office Open XML standard, XLSX is the default format when creating a spreadsheet using modern versions of Excel. Microsoft introduced this open format largely due to increased competition from Open Office and its Open Document Format (ODF). The XLXS format replaced the proprietary XLS format that Excel used previously.

RELATED: What Is a .DOCX File, and How Is It Different from a .DOC File in Microsoft Word?

How Do I Open an XLSX File?

Because XLSX files have become standardized, you can open them in many applications on different platforms. Although Windows doesn’t natively open them unless you have a copy of Microsoft Office 2007 or later, you can download a third-party open-source application like Apache OpenOffice or LibreOffice to open your files.

Mac users just need to double-click on the file and it will open in the Apple Numbers application.

If you’d rather store, open, and edit all your Office Open XML files in the cloud, you can do so by uploading your document via Excel Online or Google Sheets.

Alternatively, if you’re a Chrome user, you can download the extension Office Editing for Docs, Sheets & Slides (an official Google extension) for your browser. It lets you upload any XLSX file directly from your local hard drive to your Google Drive by dragging and dropping it into any Chrome tab.

RELATED: How to Work with Microsoft Office Files in Google Drive