The process of building links to your website is an important part of search engine optimization to increase the ranking of your website. Prior to 2012, that process was fairly easy in that you simply needed to build a blog and link every blog entry to your website with various anchor text keywords. Any link that points to your website from another website is known as "inbound linking."
For every blog entry you created using that scenario, you would be able to increase your search ranking a little bit more. At the time, Google was counting the total number of links as part of your ranking.
All that changed in 2012 when Google started filtering out low quality blogging websites and discounting the total number of links from a single domain, favoring instead, the total number of different domains linking to you. In other words, blogging on another website that links to you is now longer a best practice. If you are still doing that you should consider moving that blog to your own website because the organic value is far more important than the links you are building.
On the other hand, according to my research in Google Webmaster Tools, it seems like Google is favorably counting many of the links it finds on social networks. When you share a website page to a social network you are creating a link between that network and your website. Even though these shared links are all on the same domain name, in my measurements, it looks as if they are being counted favorably toward your "inbound link graph."
Background Information: The "Inbound Link Graph" is the phrase used when talking about all the links that point to your website. If most of the links come from a few domain names, like blogs, then your graph is said to be unnatural. When you have many links from different domain names, and from social networks, then your graph is said to look natural, or organic.
More Background Information: All links on the internet are not treated equally. Links from small websites are usually not as important as those from large websites. Sometimes that website owner will add the "rel=nofollow" attribute to the link. This nofollow setting is supposed to tell the search engines to ignore the link, and not to include it in the inbound link graph for a website. Keep this in mind as you read the rest of this Nugget.
So the links from different social networks have some type of value towards link building, and some networks are more important than others.
In case you haven't heard yet, sharing your website links to Google+ is an important part of your link building. From my point of view, Google owns this network and they want people to use it, so it only makes sense for their profits (because they are a public company) to give some type of hidden incentive for people to use it.
Any shared post you put on Google+ are found and immediately included as reputable inbound links for your website. Links from Google+ back to your website DO NOT have the nofollow attribute, which means the Google Search system has full permissions to include it in your link graph.
Every time you share a blog post to Google+ it is counted, so post often.
On the other hand, I continue to share links to my personal Facebook page and to 2 of my business Facebook pages. I share links daily. Google never finds the links I share to my personal profile, which is nothing new since Google does not read personal accounts.
All the links on Facebook have the nofollow attribute, which means the search engines are not supposed to include them in your link graph. Most of the time this is true, but apparently Google is still finding links occasionally.
The last time Google found a link I shared to Facebook was September 9, 2011. So it seems that, as far as SEO is concerned, Facebook shared links are worthless for Google search ranking. Since Facebook and Google are rival companies it makes sense that Facebook would use nofollow to tell Google to go away.
In the past I've also written about how difficult it is to get people to leave Facebook and go to your website. Overall, the only thing Facebook seems to be good at is interactions between big brand names and people who already know who they are.... oh, and Facebook is good at wasting your time too.
Share to Twitter are found far more often by Google than shares to Facebook. In the past Twitter used to apply the nofollow attribute to all the shared links, but according to my testing that isn't the case anymore.
Since Twitter has an uncountable number of tweets daily I surmise that it is impossible for them to keep up with discovering all the new posts. Once upon a time Twitter and Google had an agreement whereby Twitter was feeding Google all the tweets through a dedicated connection, without having to spider each tweet manually. That connection no longer exists, which means Google is stuck doing it the manual way now, and is seems to me that Google can't keep up with that manual process.
I've been able to measure that Google immediately discovered more of my tweets as soon as I started tweeting more than 6 times a day. At a rate of 6 tweets per day it seems like 1 tweet per month is counted towards my inbound linking efforts, which in turn helps website ranking in Google SERPs.
Remember that, when it comes to Twitter, the real reason you are using it is to get people to click over to your website. More people will visit as you ramp up your tweeting volume.
Now on to Pinterest... All of the images you share to Pinterest should include a link back to your website. Pinterest also applies the nofollow attribute, but is seems like Google is ignoring it. As a long term test I've been pinning every day for the last 6 months. That's about 30 pins per month, and Google seems to include 1 per month as part of my link graph.
When you pin an image to Pinterest the hope is that someone will click on it and visit your website, which would make you money. But the other hope is that people will "share" your pin. A shared pin is called a "re-pin," and it turns out that even if you don't make any money from this, the re-pins are more valuable for your link graph than your original pin.
Google seems to give link building credit each and every time someone re-pins one of my original pins. Even though the nofollow attribute is included on the link, Google is ignoring it and including it in the link graph. If Pinterest isn't bringing direct money to your store, consider it as part of your link building efforts.
YouTube is another social network owned by Google. Unlike Google+, the links on YouTube have the nofollow attribute, but Google still finds them and includes them as your link building efforts. To make this work you need to include the URL of your website in the description of each video you post. I don't have much more to say on this other than it works, and has worked for many years.
As you can see, the social networks are a good method to build links to your website. The direct returns on investment of time can't always be measured in direct money in your cash drawer, sometimes it's the small things that accumulate as a snowball effect.
If you are looking for 1 network where you can get the most bang for your buck, the clear answer is Google+. According to this analysis, the clear looser is Facebook. Ramping up your frequency of tweets can turn up the value of Twitter more easily than building a video channel on YouTube, or trying to get re-pins on Pinterest.
Social. Get involved.