1. Unrelated Keywords
First, we’re talking about the practice of stuffing your content with irrelevant keywords in an attempt to manipulate your page’s ranking in search engine results pages. Adding multiple keyword variations where they don’t add value will create a poor user experience.
Google exemplifies this concept as:
lists of non-value-added telephone numbers;
blocks of text listing cities and states for which a web page is trying to rank;
repeating the same words or phrases so often that it seems artificial.
2. Cloaking
This involves showing one part of your business opportunity seekers email list content to users and another part to search engines. Websites that practice black hat SEO will do this to rank their content for a variety of terms that are irrelevant to their content. Spam websites often do this to try to prevent a search engine bot from discovering the spam content, which they then serve to users.
Adjusting your content for different user groups is acceptable. For example, you might reduce the size of your site when someone visits it from a mobile device. Or, you might change the language of a page based on the country of the visitor. These examples are acceptable, as long as you’re not just changing the content that appears to search engine crawlers.
While there is no clear rule to determine what is acceptable or not, the main advice is to ask yourself: is what you intend to do feasible for the user?
3. Sneaky Redirects
A redirect involves sending someone to a different URL than the one they initially clicked on. Therefore, Black Hat SEO uses redirects for other than their intended purpose. That is, redirecting an authoritative page with many backlinks to an irrelevant one , just to boost its position in search results.
Redirects should only be used for the purpose for which they were designed. This could be if you change your website domain or consolidate two pieces of content.
It is also acceptable to use JavaScript to redirect users in some situations. For example, LinkedIn redirects you to someone's full profile when you are logged in, rather than showing the public version of a user's profile when you are logged out.
4. Low quality content
Low-quality content has no value to the user , so this is also a common practice in Black Hat SEO. The most common examples here involve copying content to your website, which since Google's 2011 update, is now easily identified.
Adding invisible keywords to your content is also a no-no . Some websites do this by making their text the same color as the page's background. This means that your page can appear in search results for those invisible keywords, even though there is no visible content about them on the page. When a user clicks on the result thinking it will be about the topic they searched for, they won't find any of the content they were looking for because the keywords are invisible!