I read an interesting post at SEOmoz about the different factors which influence how valuable a link is in terms of improving the target page’s search engine rankings, and wanted to share it with my colleagues. But being a busy lot I knew they probably wouldn’t have time to read the whole thing, so below is my heavily summarised bullet-point version – I hope it does justice to the original article (which I recommend you read, if you have the time).
1) Get lots of links from third party websites.
2) Make sure those links use anchor text which includes relevant keywords.
3) Links from sites with high PageRank are better than links from sites with low PageRank.
4) Stay away from spammy sites (both in terms of inbound and outbound links).
5) Links from high-authority sites are good – but ‘authority’ is still a bit hard to define.
6) Get links from a wide range of different websites, diversity of links is good.
7) Links between sites which have a clear pre-existing relationship don’t have as much value.
8) Links should be embedded in a website’s main content area – sidebar and footer links are less valuable.
9) Links from websites with content that is relevant to the client’s website are thought to be more valuable – but don’t get too hung up on this, good links from generic sites are also helpful.
10) Links that are embedded in editorial copy are better than other kinds of links.
11) Geography may play a part in SEO.
12) Links that use the ‘nofollow’ tag are generally worthless, but there is speculation that the search engines do give some value to nofollow links on high authority sites like Wikipedia.
13) Plain HTML links with good anchor text are good. Image links with good alt text (the stuff that pops up when you hover over a picture ) are good. Non standard links, which are embedded in weird bits of code are not good.
14) If the page linking to your website also links to spammy sites, this is not good – it is what SEO people refer to as being in a bad neighbourhood.
15) Search engines sometime penalise websites for spammy behaviour. Links from a website which is being ‘punished’ are not good.
16) If you have a lot of links that look similar (badges, widgets, syndicated press releases, etc) there is speculation that these links are not as valuable as the kind of varied and diverse links you would find in editorial copy.
17) It is better to build up lots of links over time than to get one sudden burst of links. Sudden bursts probably don’t hurt, but they should be part of a long-term SEO campaign.