First, what is meta tags
meta tag provides metadata about the HTML document (Metadata is information about data), the metadata is not displayed on the page, but for a machine readable. For example meta is used to set a keyword, set the page description, setting author, character set, set the page timed jump and so on. meta tags placed in the head tag, a set of meta-search engine registration, search engine optimization has a crucial role in rankings.
Two, meta tags role
meta data is available in the machine interpretation, tells the machine how to parse this page, there is a purpose that can be added to the server sends the browser http header content
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8"> //声明字符编码
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
</body>
</html>
Three, meta tags common use
<!-- 声明文档使用的字符编码 -->
<meta charset='utf-8'>
<!--百度禁止转码-->
<meta http-equiv="Cache-Control" content="no-siteapp" />
<!-- 页面描述 -->
<meta name="description" content="不超过150个字符"/>
<!-- 页面关键词 keywords -->
<meta name="keywords" content="your keywords">
<!-- 禁止自动翻译 -->
<meta name="renderer" content="webkit">
<!-- 较重要的是viewport属性。常用于移动端设计。 -->
<meta name="viewport" content="width=device-width, initial-scale=1">
content 参数：
width viewport 宽度(数值/device-width)
height viewport 高度(数值/device-height)
initial-scale 初始缩放比例
maximum-scale 最大缩放比例
minimum-scale 最小缩放比例
user-scalable 是否允许用户缩放(yes/no)
