Special Meta tags and their purpose!

[Deelip]

Hi,

Can anybody suggest me about these tags
<meta http-equiv="Cache-Control" content="no-cache"/>
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />

What are the purpose of these tags and is there any harm in SEO if we put these tags in our website. Please let me know your valuable inputs.

Thanks,

[AussieWebmaster]

I am interested in learning more about these myself.

They are used to speed page load by inhibiting caching and also force the latest edition of the page to load every time from what I can gather

anyone else?????

[beu]

Folks use <meta http-equiv="pragma" content="no-cache"> and <meta http-equiv="Cache-Control" content="no-cache"/> so that users don't see a cached version of pages which have been updated since the last time the user visited. Both these should be used when a no-cache request is made.

There is a belief that sites not allowing cached pages might trigger Google's cloaking signal.

As a result some webmasters use <meta name="Expires" content="date"> so as to allow the page to be cached but also to update the cache on a specific date. In this case, 0 is an illegal "expires date" because the date must be in GMT format but it's interpreted as meaning NOW!

Search engines may delete or reschedule a revisit if dates have expired but that is not always the case.

If you want to tell engines that content has expired it is best to use their new format.

http://googleblog.blogspot.com/2007/07/robots-exclusion-protocol-now-with-even.html

Hope that answers your question!

[jimbeetle]

Http-equiv metas have no SEO value. They're simply used by most servers to form http headers for certain elements. For the above, the server would read those elements and include them in the http header as:

Cache-Control: no-cache
Pragma: no-cache
Expires: 0

I've never really understood the difference between Cache-Control and Pragma. Just reread the specs and th eyhurt my brain ;).