!DOCTYPE html PUBLIC"-//W3C//DTD XHTML 1.0 Strict//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"The Transitional DTD includes everything in the strict DTD plus deprecated elements and attributes:!DOCTYPE html PUBLIC"-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"The Frameset DTD includes everything in the transitional DTD plus frames as well:!DOCTYPE html PUBLIC"-//W3C//DTD XHTML 1.0 Frameset//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd" I want to know what is the Purpose of Strict,Transitional & Frameset Attribute........I mean to know when I've to use Strict, Transitional or Frameset Attribute.......Please explain in Details....I'll be very thankful to you. Ok bye Take Care