Cloaking is the display of different content between users and search engine crawlers.
For example, when a general user accesses it, a normal page is displayed, but when a google crawler comes, a page studded with keywords that seem to be important for SEO is intentionally cloaking intentionally. If you do, Google may delete the worst index.
There are several techniques for cloaking, but the most common one is content switching using a user agent.
User agent is the search engine crawlers this technique to switch in case it is not the case of an add-on such as a browser user agent can be easily ascertained by modifying the. In this case, you can confirm whether the page has been changed by disguising your browser as google bot and accessing.