There are some SEO techniques that are penalized by search engines. In many cases, these bad practices, called Black Hat SEO, take place mostly out of ignorance, which becomes essential reading recommendations, guidelines and lines of action to correct the major search engines Webmaster. Penalties by the search engines can range from light drops to position ban or total expulsion of the search index.
Some of the Black Hat SEO techniques to avoid are:
Hidden or tiny text
Entering text the same color as the background on the website, or with an almost illegible size (perhaps writing text with a size less than 10) are easily detectable practices by search engines, so the penalty is warranted.
Overloading Keywords (Keyword Stuffing)
The act of introducing excessive keywords aimlessly in the website, the source code or meta tag “keywords” is a matter of penalty, especially if those words have little or nothing to do with the theme of our website.
These are pages full of keywords with little or no actual content whose sole purpose is to redirect traffic to the website or domain.
Technique that shows different versions of web page to the search engine robot and the user’s browser.
These are pages with a disproportionate number of links with the sole mission to increase artificially the sites listed. If the farm is penalized the mere inclusion of our web site may harm it.
Copied or duplicated content
In order to maintain quality results in the indexes, search engines do not provide good positions to sites whose contents are mostly taken from others, or directly stolen. Search engines are constantly working on the detection of these and other illegal techniques in an effort to remove or bury results of little or no quality.