.xlsm is one of the file extensions for files created by Microsoft Excel (Excel 2007 or later). This format can store macros written in VBA.
Starting from Excel version 2007, Microsoft changed the format of the Microsoft Office files.
Formerly, Microsoft used the BIFF (Binary Interchange File Format) binary format (.xls
, .doc
, .ppt
). It now uses the OOXML (Office Open XML) format. These files (.xlsx
, .xlsm
, .docx
, .docm
, .pptx
, .pptm
) are zipped-XML.
.xlsx
is the new default Excel format, it cannot contain any VBA (for security reasons as stated by Microsoft).
.xlsm
is the new Excel format that can store VBA and execute macros.