Forum Moderators: phranque
To know what kind of HTML file you have, you need to write with a specific standard in mind (e.g. HTML 2.0 [w3.org], HTML 3.2 [w3.org], HTML 4.01 [w3.org], XHTML 1.0 [w3.org]). If you didn't write with a specific standard in mind, then you need to pick a standard right now and adjust all your HTML accordingly. An easy way to do this is to use HTML Validator [validator.w3.org] to check the syntax and correct all the errors.