docx In an effort to create an open document standard, Microsoft in collaboration with ISO/IEC and Ecma, developed the Office Open XML standard in 2006. One of the filename extensions supported in this specification is the .docx extension, a text document filename extension. The .docx was introduced in Microsoft Office Word 2007 and has been supported ever since in later iterations. It has become the default filename extension for all text documents produced using Microsoft Office Word. Given the open source nature of the XML specification, more alternative document processing applications support read and write capabilities on documents saved with the .docx filename extension. This is in comparison to the .doc filename extension which is a proprietary asset owned by Microsoft.
lit The .lit filename extension, short for literature, is a proprietary filename extension of the eBook file format LIT developed by Microsoft. The format was initially released in 2000 and at the time was only compatible with Microsoft Reader. Though DRM support was one of the strong selling points of the LIT format, wide spread DRM circumvention discounted its utility in favor for competing open formats. This among other reasons caused Microsoft to officially discontinue support for the format by 2011 and cease further sales of eBooks based on the format completely by 2012.