【Meta】
The Meta tag is divided into two parts: HTTP header information (http-equiv) and page description information (name)
(1) http-equiv is similar to the header protocol of http, it responds to the browser with some useful information to help display the content of the web page correctly and accurately. Commonly used http-equiv types are:
① content-type and content-language (display character set settings)
<meta http-equiv="content-type" content="text/html;charset=utf-8">
<meta http-equiv="content-language" content="zh-CN/EN/FR">
(charset-character set; gb2312-national standard Chinese character code; big5-traditional Chinese code; utf-8;)
② refresh (refresh)
Automatically refresh once after 10 seconds: <meta http-equiv="refresh" content="10">
Automatically jump to another file after 10 seconds:
<meta http-equiv="refresh" content="10;url='The url of the file to be connected' ">
③ page-enter/page-exit (effects when the page is loaded or called out)
<meta http-equiv="page-enter" content="blendtrans(duration=0.5)">
<meta http-equiv="page-exit" content="blendtrans(duration=0.5)">
(blendtrans is a kind of dynamic filter, which produces a fade effect)
Revealtrans effect
<meta http-equiv="page-enter" content="revealtrans(duration=#,transition=#)">
<meta http-equiv="page-exit" content="revealtrans(duration=#,transition=#)">
(duration represents the duration of the filter effect (seconds); transition represents the filter type (0~23))
④ content-script-type (script related)
<meta http-equiv="content-script-type" content="text/javascript">
W3C specification specifying the type of script in a page
⑤ When http-equiv="pics-Label", content indicates the level of page content
⑥ When http-equiv="expires", content indicates the date when the page expires
(2) The name describes the web page and corresponds to the content (web page content), so that the search engine robot can find the classification
(At present, almost all search engines use online robots to automatically find meta values to classify web pages)
<meta name="keywords" content="Keyword1, Keyword2, Keyword3, ...">
<meta name="keywords" lang="EN" content="vacation,greece,sunshine">
<meta name="keywords" lang="FR" content="vacances,grè:ce,soleil">
(The usual role of meta is to specify keywords that search engines use to improve search quality. When several meta elements provide document language dependency information, the search engine will use the lang feature to filter and display search results through the customer's language preference)
<meta name="description" content="Web page description">
(Submit the content of the homepage of the web page to the search engine)
<meta name="robots" content="all/none/index/noindex/follow/nofollow">
(tell search bots which pages need to be indexed and which don't)
all: the file will be retrieved and the links on the page can be queried
none: the file will not be retrieved, and the links on the page will not be queried (same as noindex/nofollow)
index: the file will be retrieved (let the robot/spider log in)
noidex: The file will not be retrieved, but the links on the page can be queried; (do not let robot/spide log in)
nofollow: The file will not be retrieved, the links on the page can be queried. (Do not let the robot/spider follow the links on this page to find it)
作者（author）<meta name="author" content="xxx，[email protected]">
Copyright (copyright) <meta name="copyright" content="The copyright of this page belongs to xxx All Rights Reserved">