Link juice in SEO – an introduction
Links, both internal on your site and external – those pointing from other sites to yours are what help search engines find and index your content. The distribution of links, particularly the quality of those linking to you and the volume is a significant search engine ranking factor. For example the bbc.co.uk linking to your site tells Google that a really influential web site is ‘voting’ for your content. Voting is a bit of an odd term to use here so it may be better to think of it that if another site feels that your content is of significance, and links to it, then that is a good reason why search engines should rank your site higher for terms relevant to that content.
Just as external links are important so are internal ones i.e. links within your site to other pages on your site. These help share the ‘link juice’ from one page to another. For example if the bbc.co.uk links to my home page I get link equity or juice not only to my home page but also to other internal pages linked to from the home page. E.g. home > http://www.andy-maclean.net/category/advanced-seo/ because that category page is linked to from the home page. It doesn’t stop there however. That juice that got to the advanced SEO category page will seap to those pages linked to on that page and this continues on and on getting diluted as it goes. Because it gets diluted you should organize your site so that your most important pages get the most link juice possible. More on that below.
Googles PageRank (PR) which ‘scores’ sites from 0 to 10 based on a complex algorithm, loosely interpreted as being concerned with the the quality and quantity of links to your site/ pages is an indication of how good the link juice flow or link equity is that is reaching your content. Hence the over infatuation of site owners to increase their PR, often at the expense of creating good content and often at the cost of incurring ranking penalties because of spammy link building techniques.
Your site will benefit from higher PR pages / sites ranking to them though it’s important to note what makes a good link is down to a number of factors such as the authority of the domain that links to you and where the link is on the page. Here’s an excellent article by Rand Fishkin on why all links are not equal.
Site architechture and link juice
As metioned the sharing and dissemination of link juice internally on your web site helps all pages rank better and is the key reason why a good site architecture is important e.g. your most important pages should always be linked to from the home page. The home page generally being linked to from every page on your site will, nearly always by default, be the page that has the most internal link juice pointing to it and it is of course usually the page on the site which has the most external links pointing to it.
Lets look at a practical example: airbnb.co.uk
Look at their current home page. Can you guess which location pages are the most important to them? Do you also notice how they have a link to the page that lists all their location guides? Simple, but smart, in terms of passing link juice to the most important pages.
So lets next look at their London page, which is linked to from their home page. Notice how they’ve included a link to all their London listings?
To recap the flow here is Home > London Guide > London Listings. It’s a nice simple and short way to get link juice flowing to the pages they want.
The implications of not having a well thought out site architecture are not only restricted to poor passing of link equity but also poor user experience. If it takes 5 clicks from landing on the site to get to the page you want thats not good.
Common issues with architecture & link juice
If you have 100s of links on a page Google will not crawl them all, it is a load on their resource. This is why airbnb.co.uk can’t list all their locations on the home page, just the priority ones. Keep the links per page to less than 150. It’s thought the more authorative the site the more resource it’s likely to be given so bear that in mind with the 150 limit suggestion.
Breadcrumbs (see below example) are a good way of ensuring flow between important pages as well as being good for user experience.
Url structure and organisation of product folders can be an issue e.g. abc.com/widget/blue/small/ is probably not as good as abc.com/widget-blue-small. This is more of a personal opinion than widely accepted fact but i’ve seen that seemingly embedding a page in a folder of a folder of a folder i.e. /widget/blue/small makes that page look like its buried deep and not a prominent and therefore important page. In projects i’ve been involved in i’ve noted that reorganising the url structures created better results, though I cant 100% pinpoint the results to that reorganisation alone.
Sub domains – if you use sub domains, e.g. blog.mysite.com, they don’t have the same link equity sharing benefits that root domains do e.g. a link on blog.mysite.com/postxyz to mysite.com/productx will not pass the same link equity back to mysite.com as it if the blog were on the root domain i.e. mysite.com/blog/postxyz. This isn’t necessarily to say sub domains don’t have so much potential to rank as I believe they can in certain instances. Also, as of fairly recently, the way Google handles sub domains as internal links has changed recently but thats a post topic for another day.
Page duplication – many, perhaps most sites have a lot of issues with page duplication, usually caused by content management systems or other instances where there are multiple pages of the same or largely the same content e.g. review pages such as abc.com/redwidget?=review1, abc.com/redwidget?=review2 etc or abc.com/index being the same as the home page. These duplicate content and paginated content issues can unknowingly dilute link equity. There are ways to fix these such as using canonical tags on alternative versions of the page to tell the search engines which is the original and only version of the page you want to be counted. I won’t go into that too much here but here’s some great articles on that subject:
Links, being vital to rankings have long been uber desirable amongst SEOs and site owners. Methods and tactics to acquire links became a vital part of growing an online business. Any old link was a good link and sites such as forums got spammed to heck with people dropping links here, there and everywhere. For a while this approach got results but it did not contribute to better search results so in 2005 Google introduced the nofollow tag, also adopted by Bing & Yahoo, which can be appended to a link and it tells the search engines to not follow the link and therefore it will not pass link equity or contribute towards PageRank. The nofollow tag is now widely used on blogs and forums to prevent the spammy submission of comments and links.
When to use the nofollow tag on your links? As suggested by Google:
- Paid links or ads
- Affiliate links
- On untrusted content i.e. if you don’t want to help the site rank better in search!
Essentially the search engines want links to be freely given and for the reason that it adds value to the page it is on.
The nofollow tag is often used on internal links incorrectly in the desire to keep certain pages out of search results. This won’t work if an external link points to that site, or its in your sitemap. If this is what you are trying to achieve you should add a no index tag to the page in question or add it to your robots.txt file. More on that here.
Ways to improve link juice
Site architecture – i’ve talked about that a bit above but some additional things to think about include:
- Your navigation – make sure it is made up of static links.
- Your navigation – include your most important pages e.g. categories in your navigation.
- Your navigation – if your template or number of category pages is significant and you’re having trouble getting them in don’t forget your footer (check out booking.com or priceline.com).
- Quick links / resources – you may have important content that isn’t desirable or suitable for the navigation. You could include quick links / resource or popular products (check out tripadvisor.co.uk).
- Alternative products – look at all the big hotel aggregators e.g. booking.com, on a hotel page they include links to alternative hotels, mostly for user experience, but it also helps share link juice.
- Don’t bury things in folders like this abc.com/widget/red/small/cheap.
- If you change a url and the content is appropriately similar you must apply a 301 redirect or lose any link juice the previous url had. This tells the search engine that whilst the url has changed the content is the same. I’ve seen a few times instances of when businesses have relaunched web sites with different url structures and not 301’d their url with total and devastating loss of top rankings as the result.
Get external links (ethically)
- An enormously broad subject i’m not going into here, suffice to say having other web sites ‘vote’ for you is, and will likely remain, an enormous contributor to your sites ability to rank well in search results.
Know your important pages and opportunities
- Do you have a category, blog post or product page which has a lot of juice going to it? If so share some of it and link to other important pages, or those that need some improvement in ranking, from that page. If you don’t know which of your pages are being linked to or have decent juice use Moz.com site explorer.
- Think of your admin pages e.g. contact us, about us etc. Because these are likely to be linked to from every page they would be good candidates to include links to other pages. You may need to do consider how to do this so they aren’t out of place though or irrelevant on that page.
Be careful about the technology you use