User-agent based cloaking is done by checking the user-agent of the visitor and serving different content to visitors based on their user-agent (i.e. if the user-agent is a search engine spider versus anybody else). It is a blackhat SEO technique, yet some websites still do it. Those of you who are doing it, keep in mind that there’s a good chance a competitor will report you if they notice you are doing this.
But if you have set your mind on taking this route regardless of its black tint, do so in a smart way. Here’s a tip: make sure that cloaked pages are not cached by SEs. This can be done via META elements. This is important because it ensures that the cloaked page for the SEs can not be seen by users who click on the “cache” link for that page in the SERPs.
Here’s a META example for Google:
<META NAME=”GOOGLEBOT” CONTENT=”NOSNIPPET”>
<META NAME=”GOOGLEBOT” CONTENT=”NOARCHIVE”>
This prevents Google from archiving the current page and also tells Google not to create any snippet based on the page content. The NOSNIPPET tag automatically triggers the NOARCHIVE for Google, but it does not hurt to include the tag anyway. Also the “cache” link will not be shown for your page in the Google search results pages.
To see if your user-based cloaking gets detected, run your site (or any other site) through the Cloaking Detector.
And, as with any black-hat SEO techniques, before doing it, check if it’s worth – and be ready to eventually suffer the consequences.
