html是超文本标记语言，现在常用到的2中文档格式是html5和XHTML 1.0 Transitiona(过渡)。
<!DOCTYPE html> <!--当前文档为html5--> <html> <head> <meta charset="utf-8"/> <!--格式编码utf-8 中文gb-2312--> </head> <body> </body> </html>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body> </body> </html>
<head> <!--设置文档编码--> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <meta charset="utf-8" /> <!--设置关键字和描述方便SEO--> <meta name="keywords" content="关键字"> <meta name="description" content="网站描述"> <!--设置移动端开发缩放比例--> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0;"> </head>