The DOCX file is the updated version of the DOC file utilized in word processing applications like Microsoft Word or Google Drive. This file type was standardized by the 2007 Version of Microsoft Word. How DOCX files operate is similar to a ZIP file. The data within is compressed and stored as XML and CSS data, essentially meaning the overall size of the file is smaller and opens up much quicker. The name DOCX comes from the combination of the old extension, DOC, and the “X” from the XML file format. Modern word processors are designed to account for this compression and will unzip any DOCX files before opening them, making for a much smoother user interface. DOCX was largely successful as a file extension due to this simplifying of the data, making it much more convenient for storage or email attachments. However, if you are attempting to open an older DOC file using a modern word processor, you may run into errors depending on the complexity of the file.