Cloaking is a black hat SEO technique where one set of content is shown to human visitors and another set of content is shown to search engines
In cloaking, human visitors are shown the actual web page, but search engines are shown a web page which is full of spammy SEP techniques such as keyword stuffing.
Cloaking by User Agent
To effectively cloak a web page, the web server must be able to determine if the visitor is a human or a search engine.
One technique for doing this is to look at the user agent field of the HTTP request.
The user agent field for a human visitor usually lists what web browser software is being used.
The user agent field for a search engine usually identifies the search engine robot.
Cloaking by IP Address or Hostname
Another technique for identifying traffic from search engines is to cloak traffic coming from the domains of search engine operators or the IP addresses used by search engine operators.
The Benefits of Cloaking
Cloaking does work in many cases to achieve improved SERPs.
Detecting Cloaking
One technique for determining if a web page is using cloaking is to view Google's cache of that web page. Unless the web page has turned off Google caching, the Google cache will show you how Google bot sees the web page. If the web page has turned off Google caching, that is also a possible indicator that cloaking is in use.
It is also possible to set your own user agent to spoof the user agent of a well known web robot, such as Googlebot. If the web page is using user agent cloaking, you will then see the cloaked page that is normally shown to Googlebot.
You can modify your user agent in Opera by selecting Tools > Preferences > Network, and then changing the "Browser identification" setting.
The User Agent Switcher Extension will enable you to change your user agent in Forefox and Mozilla.
Another good tool for detecting cloaking is WANNABrowser. WANNABrowser is a web-proxy which will show you the HTML source for any page on the Internet, while letting you set your user agent.
The Penalties for Cloaking
Cloaking is in violation of most search engine policies and is very likely to get your site banned.
In cloaking, human visitors are shown the actual web page, but search engines are shown a web page which is full of spammy SEP techniques such as keyword stuffing.
Cloaking by User Agent
To effectively cloak a web page, the web server must be able to determine if the visitor is a human or a search engine.
One technique for doing this is to look at the user agent field of the HTTP request.
The user agent field for a human visitor usually lists what web browser software is being used.
The user agent field for a search engine usually identifies the search engine robot.
Cloaking by IP Address or Hostname
Another technique for identifying traffic from search engines is to cloak traffic coming from the domains of search engine operators or the IP addresses used by search engine operators.
The Benefits of Cloaking
Cloaking does work in many cases to achieve improved SERPs.
Detecting Cloaking
One technique for determining if a web page is using cloaking is to view Google's cache of that web page. Unless the web page has turned off Google caching, the Google cache will show you how Google bot sees the web page. If the web page has turned off Google caching, that is also a possible indicator that cloaking is in use.
It is also possible to set your own user agent to spoof the user agent of a well known web robot, such as Googlebot. If the web page is using user agent cloaking, you will then see the cloaked page that is normally shown to Googlebot.
You can modify your user agent in Opera by selecting Tools > Preferences > Network, and then changing the "Browser identification" setting.
The User Agent Switcher Extension will enable you to change your user agent in Forefox and Mozilla.
Another good tool for detecting cloaking is WANNABrowser. WANNABrowser is a web-proxy which will show you the HTML source for any page on the Internet, while letting you set your user agent.
The Penalties for Cloaking
Cloaking is in violation of most search engine policies and is very likely to get your site banned.