A CRX file is an extension that adds extra features or themes to the Google Chrome web browser. It is saved in a compressed format and may contain .JS, .JSON, and other files, such as images and executable programs. CRX files are used for installing browser addons such as games, ad blockers, and news readers.

Chrome extensions can be installed manually by dragging CRX files to the Extensions window. You can open this window by choosing Window → Extensions from the application menu, or by setting your browser address to chrome://chrome/extensions/. Chrome extensions are typically installed by clicking the "+ Add to Chrome" button for an extension on the Chrome Web Store. After clicking the button, Chrome downloads the extension, unpacks it, and then installs it without the user having to interact with the CRX file. After installation, Chrome automatically deletes the CRX file. NOTE: CRX files use .ZIP formatting. However, they also contain a custom header section of the file, so standard Zip decompression utilities may not be able to decompress them.