HTML cannot directly create a file on its own
Use a form to send data to a server that creates the file
Use JavaScript to generate a file in the browser
Create a Blob with the file content
Create an object URL from the Blob
Create an anchor element with the download attribute
Set the anchor href to the object URL
Set the anchor download filename
Trigger a click on the anchor element
Revoke the object URL after download
Use server-side code if you need to save the file permanently