You can open XLSX file online or offline with Microsoft Excel application, part of Microsoft Office software suite. XLSX file format was introduced starting from Microsoft Excel 2007. Prior to that, Microsoft Excel used XLS file format which is based on Compound File Binary Format (CFBF).
XLSX file is based on Office Open XML file standard which is an XML based file format designed by Microsoft for document exchange. Office Open XML (OOXML) file standard is licensed as ISO/IEC 29500 and ECMA-376.
XLSX file contain table-based information where data is stored in rows and columns. Besides storing rich text and formulas in the table cells Microsoft Excel could also store charts, graphs, shapes, video, audio, images and many other content types embedded into XLSX file. Excel formulas allow coding complex calculations into the cells and even reference other Microsoft Excel files.
Since XLSX file is XML based it is possible to open it using text or XML editor. To do this you need to unpack content of the XLSX file first. To do this you should change XLSX file extension to ZIP and extract content from it. After content is extracted you will see several XML files files with table properties, styles and content. For specifics about XLSX Office Open XML format read OOXML standard specification.
Besides formulas XLSX file can contain complex software code based on Visual Basic macro language. Macros can create very complex and useful Excel tables but at the same times there are some dangers in them. Around 1999 when macros were just recently introduced lots of hackers used them to code viruses and embed into Microsoft Office files. These viruses caused significant damage to individual users and corporations and after that macro functionality was disabled from Microsoft Office. Now macro execution can start only after user explicitly agrees to start it. Still many macro virus writers mask viruses as a valid document and try to make impression that macro execution is necessary to view the document (for example to change encoding of incorrectly encoded document). That is why it is important not to open XLSX files from unknown and untrusted sources.
XLSX Quick Info | |
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Microsoft Excel OOXML File | |
MIME Type | |
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet | |
Opens with | |
Microsoft Excel | |
Microsoft OneDrive |