XLTM files are spreadsheet templates created with Microsoft Excel versions 2007 and above. Microsoft Excel is compatible with multiple operating systems and it's currently one of the top applications for creating and editing spreadsheets.

Excel stores data in worksheets, each having a grid of cells arranged in columns and rows. Cells can contain text and numbers of various fonts, colors and sizes. The default file format of Microsoft Excel is XLSX. These files can include charts, pivot tables, graphs and mathematical functions and also support the Visual Basic macro programming language for applications.

XLTM templates are used to store the entire structure of a document. By creating a template the whole process of building a specific type of spreadsheet from scratch can be avoided. Once the template is created, users can simply add text and other content and save it. Excel will create a new file which will inherit all formatting options and will leave the XLTM file unaltered.

Additionally, XLTM files can also store Macros. Embedding them into the document's structure is done via the Macro Recorder included in MS Office which can save command sequences and create macros to replicate them automatically.