The extension of MS word is:

🧠 Explanation:

The .docx extension is used for Microsoft Word documents, introduced with Office 2007. Based on XML, it supports advanced formatting, images, and text, making it a standard for professional and personal documents. Unlike the older .doc format, .docx offers better compression and compatibility across platforms. It’s widely used in business, education, and administration for reports, letters, and resumes. The extension ensures seamless sharing and editing, reflecting Word’s dominance in word processing. Its adoption highlights technological advancements in document management, enabling efficient communication and data organization in digital workflows globally.