What is the default file extension for most Word documents?

The default file extension for most Word documents is .docx. This extension was introduced with Microsoft Word 2007 and has since become the standard for saving documents in the Word format. The .docx format uses a compressed file structure and is based on XML (Extensible Markup Language), which allows for better data management and enhances the capabilities of documents, such as improved recovery of information and smaller file sizes compared to its predecessor .doc.

Choosing .docx as the default extension signifies the evolution of Word's features, supporting advanced elements like rich media and improved collaboration tools. In contrast, older formats like .doc (which is from earlier versions of Word) and formats like .txt and .pdf serve different purposes. .txt is a plain text format without any formatting options, whereas .pdf is a document format designed for preservation and uniform viewing across platforms, not for editing. Thus, .docx is identified as the modern and versatile choice for standard Word documents.