Search engines Ranking is what SEO is all about. You tweak your pages trying to "meet search engine's requirements" and gain high ranking in the search engines' results. However, what are these "requirements"? We all know search engines are nothing but robots, computers that follow a certain program to determine which site is more relevant to a query and which one is less useful. Yes, when chasing search engines ranking, we are just struggling against a machine—a powerful instrument with a sophisticated program though it may be, but a machine nevertheless. However, we are humans with much more flexible minds, and our creative approaches will let us crack search engines’ ranking algorithms if we input time and proficient efforts.

Search engines do not reveal their ranking algorithms, for doing so would be equal to giving each SEO a nuclear weapon and pushing them into a mortal combat against each other. The World Wide Web would turn into a giant heap of over-optimized pages stuffed with ads and nonsensical content. In other words, if search engines kept their ranking algos open, they would confine themselves to showing not RELEVANT, but OPTIMIZED pages on the top, and today, there's indeed a great gap separating these two sets.

It is true that the search engines' ranking algorithms are secret, and we have to submit ( :) ) to the fact that we cannot buy this information from the search engines or find it, say, on Google.

What are the ways of discovering the path to high search engines ranking, then?

The word SEO (search engine optimization) first sounded nearly ten years ago. Since then, many researchers, driven by financial, professional, or scientific interests, tried to crack ranking algos by experimenting. Thus, several years ago, it was discovered that putting many keywords in the META and TITLE tags can improve rankings in the search engines for these keywords, giving an optimized page a competitive edge over those probably more relevant but less optimized. The search engines' ranking algorithms of those days were really simple enough to allow invisible tags (such as META keywords and META description) influence the actual position of that page in search results.

This gap was quickly discovered by spammers of all kinds who didn't leave any chance to their competition to appear on the top of the search results. The importance and benefit of good search engine positioning and organic rankings wasn't as well-recognized then, so it was mostly advanced optimizers themselves, driven by sportive passion, who tried to outrank one another.

But search engines quickly understood their vulnerability and reacted by shifting the importance from the invisible on-page elements (like the META tags) to visible and significant page areas (such as the TITLE tag) and to the off-page factors like inbound links, which made them almost completely bulletproof since these ranking factors are beyond the scope of webmaster's direct influence.

To that moment, the profitability of having organic search engines ranking became clear to a larger amount of website owners ranging from small businesses that did optimization themselves or hired an SEO to big players with the ability to spend thousands on their search presence and strategy. Therefore, search engines still needed to keep their algorithms secret and stick to their main principle: same rules and equal chances for everybody.

Search engines' ranking algorithms became more and more sophisticated, and Google became famous for its art of discouraging search engine optimizers. Search engines say they are "committed to providing relevant results," but they also have another hidden reason to make artificial achieving of high rankings more difficult—a business owner unable to gain rankings for free will agree to pay a reasonable amount for Web visibility, buying a place in the "sponsored results" column.

Nowadays, search engines ranking are done by applying algorithms that take into account elements such as the page contents, the URL of the page, the TITLE tag, and HTML headings (H1-H6). Also included in the ranking are words that are in bold, words that are used in links to other pages, words and phrases that are used in the beginning, and, at the end of the text, the number of links from other pages and sites that point to this page, the text used in these links, the authority of the linking site, and even the number of other links on the linking page. Google is said to apply additional algorithms such as like Hilltop, Sandbox, and PageRank for ranking pages more relevantly, and all of them will be described and discussed in this section.

Hilltop is an algorithm that was created in 1999. Basically, it looks at the relationship between the "Expert" and "Authority" pages. An "Expert" is a page that links to many other relevant documents. An "Authority" is a page that has links pointing to it from the "Expert" pages. Sandbox refers to an algorithm that detects how old a page is and how long ago it has been updated. Page Rank is an absolute value which is regularly calculated by Google for each page it has in its index. The number of links you've gotten from other sites outside your domain matters greatly, as does the link quality. The latter means that in order to give you some weight, the sites linking to yours must themselves have high a Page Rank in addition to being content-rich and regularly updated.