How to detect the visitor's IP address using HTML?

Question

How can i detect the visitors IP Address using HTML for my website? I have a contactform.html and a formsent.html. And when formsent.html sends the contact info to my email

Answer 1

You can't.

HTML is a markup language, not a programming language. it doesn't "do" anything - it just structures content.

You need to use a programming language, such as PHP, ASP, etc.