Meta tags are generally used to include information about a document such as author name, creation date, copyright information etc. They always placed between the <HEAD> tags of an HTML document.
Each Meta tag has two important attributes:
<META HTTP-EQUIV="some_name" CONTENT="some_content"> OR <META NAME="some_name" CONTENT="some_content">
The HTTP-EQUIV attribute takes one of the values mentioned below:
<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html"> <META HTTP-EQUIV="EXPIRES" CONTENT="May 1, 2002 00:00:00 EST"> <META HTTP-EQUIV="CACHE-CONTROL" CONTENT="no-cache"> <META HTTP-EQUIV="CONTENT-LANGUAGE" CONTENT="hi"> <META HTTP-EQUIV="REFRESH" CONTENT="5">
Note that all the META tags with HTTP-EQUIV attributes also contain the CONTENT attribute.
The HTTP-EQUIV=”REFRESH” demands more attention here, so let us have a detailed look at it.
The tag above simply refreshes the contents of the page in 5 seconds. However, you can supply a URL to this tag, which redirects users to that page.
<META HTTP-EQUIV="REFRESH" CONTENT="2; URL=new.html">
This takes the user to new.html after 2 seconds.
Note that there is only one set of quotes that encloses the content of CONTENT. Both the time in seconds and the URL are inside the same quotes.
A cheap trick is to construct a looping (or non-looping) slide show making use of these tags. Let’s say you have three html pages named slide1.html, slide2.html and slide3.html. You can make a looping slide show by including the appropriate META tag in each document.
<META HTTP-EQUIV="REFRESH" CONTENT="10; URL=slide2.html">
<META HTTP-EQUIV="REFRESH" CONTENT="10; URL=slide3.html">
<META HTTP-EQUIV="REFRESH" CONTENT="10; URL=slide1.html">
To start the slide-show, load slide1.html in the browser. After 10 seconds, slide1.html is replaced by slide2.html, which is again replaced by slide3.html after 10 seconds. Finally, after another 10 seconds, slide1.html replaces slide3.html and thus, the slide-show keeps on looping. Note that the <META> tag is placed in the head section of each document.
Though there are some fixed values for the NAME attribute, you can construct your own meta tags with it. Let’s look at the important values
<META NAME="KEYWORDS" CONTENT="movies, hollywood, actors"> <META NAME="COPYRIGHT" CONTENT="2001, Some_Company_Name"> <META NAME="DESCRIPTION" CONTENT="Information on the greatest movies ever"> <META NAME="AUTHOR" CONTENT="your_name"> <META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">
The email message in which Marc Andreessen announced the release of NCSA X Mosaic browser hasn't been lost in time. It still exists! Though there were other web browser before it, Mosaic is generally credited to have made the "WWW explosion". [more...]