White, grey or black hats are just a term used by those who work in the search industry to easily explain tactics to those outside the industry.
A hat color is simply a tactic used to help a site rank. The color is determined by how pure your tactics are or how closely you stick to a search engine’s terms of service or conditions.
Black Hat SEO
Lower quality sites tend to not to meet as many points on the algorithm, so they tend to use fewer white or gray hat techniques and lean toward the black hat where a site with great content, code, design, internal links will be able to rank without risking penalty, so they will generally stay on the lighter side of life.
Google or your search engine may not like a certain tactic, but that doesn’t make it bad.
Grey Hat SEO
Gray hat is a tactic that is merely a mixture of pure white, do only what a search engine tells us, and then add a dash of strategies that bend the rules a little.
Gray Hat SEO would write better content in great quantities, knowing it isn’t perfectly relevant, but making sure it is of some quality, relevance, and substance.
This method is commonly used to help speed up results, but minimize the risk of penalties by the search engines.
If you use a white hat tactic, it means you staying within the terms and conditions set by your chosen search engine.
It’s actually a pure and untainted approach, going by the rules. If you do so, when an update comes it won’t affect you, as the police officer (the search engine) is looking for the rule breaker.
Anyhow, for many reasons, a true white hat SEO is as rare as hair on a bald. Impatience, budget, and lack of understanding all factor into the need for a gray hat plan.