In search engine optimization (SEO) terminology, Black Hat SEO refers to the use of aggressive SEO strategies, techniques and tactics that focus only on search engines and not a human audience, and usually does not obey search engines guidelines.
Some Examples of Black Hat SEO techniques include :
• Stuffing words
• Invisible text
• Adding unrelated keywords to the page content
• Page swapping (changing the webpage entirely after it has been ranked by search engines).
Black Hat SEO is more frequently used by those who are looking for a quick financial return on their Web site, rather than a long-term investment on their Web site. This may result in your Web site being banned from a search engine.
On the other hand, white Hat SEO(Ethical SEO) refers to the usage of optimization strategies, techniques and tactics that focus on a human audience opposed to search engines and completely follows search engine rules and policies.
Some Examples of White Hat SEO techniques include :
• Using keywords and keyword analysis
• Back-linking and link building to improve link popularity
• Writing content for human readers.
White Hat SEO is more frequently used by those who intend to make a long-term investment on their website.
life’s not always black or white, the same for SEO. Gray Hat SEO, is a little white and a little black.
Gray Hat SEO is not something between Black Hat and White Hat, but rather "the practice of tactics/techniques which remain ill-defined by published material coming out of Google, and for which reasonable people could disagree on how the tactics support or contrast with the spirit of Google’s published guidelines.
Example: Guest posting.
Gray Hat SEO changes periodically; what's considered Gray Hat one year could be classified as Black or White Hat the following year, technology evolves and rapidly changes.