I am somewhat confused with what DTD declaration/!DOCTYPE to use on my site. Currently I have none and it appears to view just fine on Firefox, Chrome, and IE but everything I am reading says you need to have one. Is there a general rule of thumb that you use in determining what DTD to use?
I located this source of info but I wasn't sure if my site is considered HTML or XHTML so I didn't know what to go with. How to I determine this?
If your document is HTML, use this:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
If your document is XHTML, use this:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"