Types of Links
When we're considering the relationships between different websites, there are 3 basic types of links connecting them.
One-way incoming links (also known as "inbound links") are links leading in to your site from other sites. Incoming links are the best types of link to get, from a marketing point of view, since they're offering you something for nothing in the form of free traffic and a boost in the search engines! Sites with a large number of relevant, on-topic incoming links are sometimes referred to as hub sites.
One-way outgoing links (also known as "outbound links") are links on your own site which connect to other sites i.e. links that will lead your visitors away from your own site. From a marketing perspective, outgoing links may be considered the weakest type of link as you are effectively giving away your traffic. On the other hand, if your site is very useful, your visitors may well come back again - and they will appreciate your site even more for its willingness to point them to other relevant resources. Sites with a lot of on-topic outgoing links are sometimes referred to as authority sites.
Two-way reciprocal links are circular link relationships, i.e. your site links out to a 3rd party site, and that site links back to yours. The links might be homepage to homepage, linkpage to homepage or linkpage to linkpage, depending on the arrangement, but they're essentially a link trade. Reciprocal links can be beneficial when you're trying to market your site, especially if they are set up between complementary sites, but their value is dropping as the search engines tend to discount such "mutual admiration" relationships.
Benefits of Incoming Links
The most immediate and obvious benefit of an incoming link is that it can bring more traffic - sometimes significant amounts of traffic - to your site. Each time a visitor sees a link to your site on a 3rd party site, there's a chance they'll click on it and be whisked over to your site. An incoming link from a very busy site or page might bring you dozens or hundreds of visitors a day from that one link!
If you work to build up more incoming links to your site, and diversify the sources of your visitors more widely, you'll be protecting yourself from the roller-coaster dips and spikes in traffic that come from relying mainly on the traffic that major search engines bring.
Incoming links are also important from a search engine ranking perspective. Search engines take a lot of factors into consideration in their algoriths, including incoming links. [An algorithm is basically a "secret recipe" that the search engine uses to decide what sites will rank where for a given search query].
While the exact way each search engine makes use of incoming link information in its overall ranking calculations is a closely guarded commercial secret, broadly speaking what they are considering is the quantity, relevance and strength of the incoming links pointing to a particular site or page. Let's take a quick look at each of these 3 factors.
Quantity is the easiest, so we can get it out of the way quickly. We're simply talking about the overall number of incoming links pointing to a particular site or page. This is sometimes known as the link popularity of a site.
Relevance is an awkwardly vague concept, but it basically relates to how much the search engine "thinks" a particular site linking to yours is somehow similar to, or on the same theme as, your own. For example, a site about private jets would not be very "relevant" to a site about deep-sea fishing, so a link from the private jet site to the deep-sea fishing site would score very poorly for relevance. On the other hand, a general site about fishing would be considered relevant, and consequently a link from that site to your deep-sea fishing site would score very well on the relevance scale. Finally, a site about deep-sea fishing linking to your own deep-sea fishing site means you just hit the incoming link jackpot, as it's about as relevant a link as you can hope to get!
The relevance of a single page or section of a site can also be important. Going back to the fishing site example, if the general fishing site had a page on deep-sea fishing, that would be of the highest relevance to the deep-sea fishing site, even if the overall site was also generally relevant.
The strength of an incoming link basically depends on the relevance and quantity of links pointing to the site/page providing that incoming link, recursively. If you've ever stood between facing mirrors and seen your reflection multiplied to infinity on either side, you'll have some idea of just how tricky recursion gets. (NOTE: in Google's case, the overall strength of a page is known as its PageRank. That's a special "Google" term...)
Bringing the 3 factors back together, your aim should be to get as many (quantity) strong (strength) incoming links as possible from pages and sites that relate to yours (relevant).
Search engines also use incoming links as a "trigger" when deciding what pages their automated spiders (programs collecting data) will visit. For example, if you put up a new site, it may take quite a while before it gets visited by a search engine spider, and indexed. On the other hand, if the search engine spots a strong incoming link pointing to your site from a "trusted" source, it will be much more likely to bump your site up the spider-queue!
So, broadly speaking, more incoming links = more traffic, and quicker and better search engine rankings. The more incoming links point to your site, the more your link popularity increases. Of course, incoming links are only going to be useful if they're from relevant sites... The more relevant an incoming link, the more credible your website appears.
Further Reading (on this site)
- How to generate incoming links
- Preparing your link promotion kit
- Requesting incoming links
- Tracking your progress