what is use of <!DOCTYPE>
i mostly used <DOCTYPE> tag in html page startup ,but never know what is use of it ,
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
why we use <!DOCTYPE> ??what if we dont use <!DOCTYPE> ?
little curious !!!!