Use of special Meta tags Cache-Control, no-cache!

[SEMPro]

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,

[tbp]

The first two:

<meta http-equiv="Cache-Control" content="no-cache"/>
<meta http-equiv="Pragma" content="no-cache" />

Are instructions to the browser to fetch a fresh copy of the page each time instead of caching it locally.

The third:

<meta http-equiv="Expires" content="0" />

Is the time that the page is considered as expired, after which robots may schedule a revisit, or delete the page from the search engine index.

So the first two won't have any effect on SEO, whereas the third will, possibly causing it to be dropped from the index unless it's set to never expire, in which case there is no point in having the tag.