XHTML three document type declarations

XHTML defines three document type declarations.
The most commonly used is XHTML Transitional. <!DOCTYPE> is mandatory.
An XHTML document has three main parts: DOCTYPE Head Body
The basic document structure is this:
<!DOCTYPE ...><html><head><title>... </title></head><body> ... </body></html>
In an XHTML document, the document type declaration is always the first line. An XHTML Example Here is a simple (minimal) XHTML document:
<!DOCTYPE htmlPUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html><head><title>simple document</title></head><body><p>a simple paragraph</p></body></html>
A document type declaration defines the type of a document:
<!DOCTYPE htmlPUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
The rest of the document looks like this:
<html><head><title>simple document</title></head><body><p>a simple paragraph</p></body></html> 3 Document Type Declarations DTD specifies the syntax of web pages using Generalized Markup Language (SGML). General markup language applications such as HTML use DTD to specify the rules for tags applied to a particular document. These rules include a series of element and entity declarations. XHTML is described in detail in the Document Type Declaration, or DTD, of the Standard Generalized Markup Language (SGML). The XHTML DTD uses precise computer-readable language to describe the grammar and syntax of legal XHTML tags. There are three XHTML document types: STRICT TRANSITIONAL FRAMESET Three XML document types for XHTML 1.0
XHTML 1.0 specifies three XML document types to correspond to the three DTDs mentioned above. XHTML 1.0 Strict
<!DOCTYPE htmlPUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/ xhtml1-strict.dtd ">
Use when you want clean markup and avoid clutter in presentation. Please use with Cascading Style Sheets. XHTML 1.0 Transitional
<!DOCTYPE htmlPUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/ xhtml1-transitional.dtd ">
Use it when you need to take advantage of the presentation features of HTML and when you need to write XHTML for browsers that do not support Cascading Style Sheets. XHTML 1.0 Frameset
<!DOCTYPE htmlPUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/ xhtml1-frameset.dtd" >
Use in situations where you need to use HTML frames to split the browser window into two or more frames.

<<: Detailed explanation of where the image pulled by docker is stored

>>: mysql8.0.23 linux (centos7) installation complete and detailed tutorial