Search engines use different signals to determine which sites to display, and in what order to display them, in response to a user’s query.
Most general search engines (Google, Bing, Yahoo, etc.) use similar signals. However, how much weight a signal is given, and what they index (content they know about) can vary.
Google publicly acknowledges using 200+ signals, although they do not tell you what most of them are. Likewise, the publicly acknowledge updating their search algorithms (notice the plural) approximately 400 times a year. Some are small and affect a few sites, others are large and may affect 30% of all searches (like the recent panda series of updates).
Therefore, one can at best provide general guidance, but know that changes can occur at anytime which will affect existing rankings. I will list a series of signals, from most control/least effect, to least control/most effect.
On Page Optimization
Used to be how all SEO was done.
Using the words/phrases that a searcher uses in their query will affect how the site ranks.
The number of times the word appears, will affect the ranking. As will placing the text in header tags (H1, etc.), bold/strong, title of the page, and higher in the page.
Be careful. You can over optimize for a phrase or keyword, and it can hurt your ranking.
The problem with this is that you have to know the phrases which your searchers are using. If you know this, you can optimize well however. Use research to find out terms that people use.
Google, and others, now also look for related terms on a page to determine what a page may be about. Example, magic can also relate to “tricks”, “illusions”, “sleight of hand”, and other terms.
Optimizing for a page is easy. The entire site takes more work, so it is assumed that this has more effect for rankings. Especially given Google’s stance of brands.
Search Engines look at the “theme” of the site. Are there a lot of pages about the same topic – which could indicate knowledge base, or is this a “one-off” type of page.
Search engines also look at the size of the site. Many pages (on the same topic) tends to be thought of as an expert in the field.
Linking between pages, within the content of the page. The number of links, and the link text (the text which is used to link) matters. This works well for really large sites. (Think how well Wikipedia does for example.)
The site can also be affected by the domain name (is the query word/phrase in the domain name). As can how long has the site been around. (Older sites are slightly better.)
When you link to an external site, you are vouching for them. So getting links from other sites matters. The more the better in most cases.
The “better” (i.e. more authoritative) site that links to you, the better for you. External links to you can’t hurt, but they may not help if they don’t appear to be very good. Think Bob’s Generic Info site vs. CNN.
Links to different pages probably help, but I’ve not seen specifics. You don’t want people just linking to the homepage of a site. Get deep links to specific pages.
Google looks at the linking text (the text in the link tag) to determine relevance as well, and uses it as a ranking factor.
There are other factors considered as well. These currently have a low value, but may change over time. Others let search engines know about your site, not necessarily rank it.
- Social factors (Google +1, Facebook Like (but not counted by Google), etc.)
- Site Speed
- Ratio of content to ads
- How often your site updates.
- Inclusion of Site Map (XML – not a link to a site map for users)
An Introduction to Search Engine Optimization (SEO) was originally found on Access 2 Learn