When website A has a link to website B and website B also has a link to website A then these are reciprocal links or link swapping - I link to you and you link to me.
I'll explain why they came to be, why everyone started ignoring them and, at the end, the power they actually still have. There's SEO potential in reciprocal links no matter what you have been told.
Before Google entered the scene search engines were pretty basic. They read what was on a page and tried to figure out what that page was about mainly by looking for keywords - words which appeared in the title, meta description, keyword tag and h1 tag as well as appearing fairly regularly throughout the rest of the page.
It was a spammers paradise persuading search engines a page was about pictures of kittens but to an Internet user it was so obviously about gambling or adult content. Spammers hijacked keywords and the search results weren't always that reliable.
Google took a slightly, but fundamentally different approach. A 'good' page was a page which other websites linked to, or at least they linked to pages on the site such as the homepage. Links from quality websites (websites that had a lot of links or links from other quality websites) would carry more weight and every page on the next would end up with a measure of quality - Page Rank.
This would flush the absolute dross out of the search results.
Its what allowed Google to enter late but quickly dominate the search market but their simple concept has needed some heavy refinement over the years as spammers fought back.
Google's first attempt was too basic. If, webmasters thought, all you needed were links then links it will be. Sure one link from a random website didn't count for much so they would create 20,000 backlinks from 20,000 different websites, all created by software at the click of a mouse.
The great thing was they could all link to each other so if you created 20,000 websites they could all have 19,999 backlinks.
At the other end of the scale every day webmasters were scratching their heads as to where they were going to get links from if they weren't prepared to pay for the 20,000 backlink type program.
It wasn't long before people like me were emailing or filling out the contact forms of any half decent website we came across. Always a simple message "If you'll link to me I'll link to you".
I'm running a health website in France, you're running a car hire website in New York. What the hell, lets swap links.
It was actually more effective at times than buying 20,000 backlinks from websites which were only lists of links. Each of the 20,000 websites only had a tiny amount of page rank to pass on. Even a small established site could offer more Page Rank than the 20,000 put together.
Very occasionally you can still stumble across these old websites on the Internet. They are the ones that have a page called 'Links' in the navigation menu. A list of links to websites that have nothing to do with their main content but because the other webmaster linked back.
"Alright already" said Google as it watched the mayhem unfold. "The backlink counts more only if it comes from a website with a similar theme. So you, Health website in France, that backlink from the New York car hire company isn't going to help much."
Any backlink still had a value, but particular types of backlinks were starting to get much more punch while others were being relegated to the same status as the spammers with their 20,000 sites.
Services sprang up left, right and center to help webmasters find theme buddies. I'm running a health website in France, you're running a health shop in California. Let's swap links.
"Gaaah", thought Google. "I hadn't thought of that" and then announced it would solve the problem by making all reciprocal backlinks count for nothing. "Come on" they said, "Work on getting real backlinks. Directories are a good place to achieve that" and this created an entire directory industry overnight dedicated to providing backlinks. But these directories, Link Farms as they became known, are a story for another day.
Webmasters deleted their links pages and everyone grumbled at Google for constantly changing the goal posts.
So why am I talking about them now?
Yes they have value and they have value even when two websites seem unrelated.
The best way to explain this is with an example. X-Cart is a website which sells shopping cart software. If you want to start an online shop X-Cart can help you make that a reality. PayPal is, well everyone knows what PayPal is.
X-Cart links to PayPal as a recommended payment processor that you can use with its software. PayPal links to X-Cart as a recommended software provider if you want to create an online shop.
Reciprocal links. Because they are reciprocal links they pass no value to each other in Google's eyes so why are they doing it?
This is time to step back from SEO and think why you're doing SEO. You do it to achieve a goal and that goal is not to do SEO. Its to sell more products, get more leads, etc. Now the PayPal - X-Cart reciprocal links start to make sense. Its a commercial thing - you scratch my back and I'll scratch yours. You send me leads for my product because some of your customers will need a product like mine and I'll send you leads for your products because some of my customers will need a product like yours.
So where is the SEO connection?
Its in the indirect SEO. Some of those leads going either way through the reciprocal links will talk about those companies, some will create backlinks to those companies but they might only have discovered that company because of the link.
You only stand a chance of getting backlinks if people are aware you exist. This is one way to make them aware.
I think, although it was a long time ago so my memory is a bit hazy, that I did actually discover X-Cart because of PayPal and since then my agency, link2light, has been responsible for the creation of many links to X-Cart from many different domains that use its software to run their eCommerce stores.
Now most search engine optimizers have left the reciprocal links boat because they only think in terms of direct SEO. If action A has no direct ranking effect they ignore it.
The question for you is what websites out there could you build a relationship with so that you both benefit. If you're a house builder in Dallas link up with an architect in Dallas. And link up with a building supplies company in Dallas. Anyone wanting a house built in Dallas is likely to need all of you so start sending each other leads.
You can have a totally legitimate 'Partners' page that is of value to your website visitors. Someone might even create a backlink to that if its a good 'All in One' list of every company and organization you need to know in order to get a house built. Win, win and win again.
Like so many other things in SEO as soon as Google said "That doesn't matter anymore" most search engine optimizers just stopped thinking about it but reciprocal links are actually great ways to grow your business and hold the potential to improve your rankings through indirect SEO.
Don't ignore that potential and start thinking who you could create reciprocal links to. Yes, some in the SEO industry will ask if you have just come through a time tunnel from 2005 - but you know what you're doing.
I'm Tim Hill, a Search Engine Optimization and Online Marketing specialist. I created this site to help others understand that SEO is not a mysterious black art!.
If your a newbie try the Getting Started in SEO page, otherwise feel free to dig around and learn more.