XHTML Day 2nd: What is a name space

xhtml| name Space

After the DOCTYPE is declared good, the next code is: Usually our html4.0 code is just , what's "xmlns" here? This "xmlns" is an abbreviation of the XHTML namespace, called a "namespace" declaration. What is the role of the name space? Atzie's own understanding is: Since XML allows you to define your own identity, the identity you define may be the same as the one defined by others, but it means different meanings. Errors can easily occur when files are exchanged or shared. To avoid this error, XML uses the namespace declaration, which allows you to identify your identity by pointing to a URL. For example: Xiao Wang and Xiao Li both defined a logo, if Xiao Wang's name space is "http://www.xiaowang.com", Xiao Li's name space is "http://www.xiaoli.com", then when two documents Exchange data, Nor does it confuse identity, because it belongs to a different name space. The more popular explanation is that the name space is to make a mark on the document, tell others, this document belongs to WHO. But this "who" uses a URL to replace. XHTML is an identity language that HTML transitions to XML, and it needs to conform to the rules of XML documents, so it also needs to define namespaces. And because xhtml1.0 cannot customize the identity, it has the same name space, which is "http://www.w3.org/1999/xhtml". If you do not understand it does not matter, at this stage we just copy the code can be. After the lang= "gb2312", specify your document in Simplified Chinese.