So you have a .docx file, and you want to edit it. A few years ago, you would have needed Microsoft Word to open and edit the file, or you would need to use a workaround, such as uploading the .docx file to Google Drive and converting it to Google Docs for editing. Now, it’s possible to use Google Docs to edit the original .docx file in Google Docs using Office Compatibility Mode–no conversion required!
The following video shows how it works. Keep in mind that editing options for MS Word .docx files in Google Docs are limited to formatting, such as bolding or italicizing text, applying different fonts, aligning text, and adding bullet lists. Advanced Word features involving inserting photos and tables or tracking changes are not supported in Google Docs (at least not yet). The video is less than four minutes long, and if you need more information, I have written about the pros and cons of Office Compatibility Mode in Google Drive.