Link juice is the currency of Google. In other words, it’s the secret sauce that allows you to beat your competitors for rankings in Google. Sure, there are some other factors that Google uses to calculate rankings (see Search Engine Optimization), but link juice is by far the most important aspect of dominating Google and in order to understand Google, you have to understand link juice.
Google looks at how sites link to each other to figure out which ones are the best. To show this in a way that’s understandable, let’s show a few examples. Let’s say that Site A and Site B are both about ’some keyword’ and would both like to rank for ’some keyword’.

Google is going to take a look at links to determine which of these two sites is likely the best. At the most basic level, let’s say that Site A gets a link from a site that Site B doesn’t get:

Site A now looks better to Google and will outrank Site B. Let’s say that Site C decides to link to Site B, as well:

Now they both look the same to Google, who will now have to look at another ranking factor to determine which one is the best. There are other factors but none of them is nearly as important as the link juice factor.
Let’s add two new sites into the mix to further illustrate different scenarios that can happen:

In the above example, we now have Site D linking to Site A and Site E linking to Site B. To figure out which site is better between Site A and Site B, Google will have to look at the sites that are linking to Site D and Site E:

In the above example, Site D has more link juice than Site E because it’s getting links from Site F, Site G, and Site H. That means that Site A has more link juice than Site B. Site A will therefore outrank Site B.
Google is able to map out link relationships on an enormous scale and that’s what makes them Google.
For competitive keywords, the ranking sites have millions of links from other sites who have hundreds of thousands of links from other sites who have links from other sites who have links from other sites.
There are also non-competitive keywords that would require very few links to get ranked #1 in Google. I have #1 rankings that were achieved because of one link. This happens because all of the other sites have zero links from other sites or they have links only from sites that have no juice.
Every keyword is different and if you want to rank #1 for your keyword, your job is to get more link juice than the other sites that currently show up for that keyword.
To increase your juice you need to get more links, especially from sites that have a lot of juice.

7 Things I Wish I Had Known About Internet Marketing Three Years Ago
January 4th, 2010 | by Court | Published in Content, Industry Commentary | 18 Comments1. Search traffic is king. When a person finds you by searching in Google or another search engine, they trust you more than they would if they find you through other sources. If Google says you’re legit, people believe that you’re legit. This traffic is many times more valuable than traffic from other sources.
2. Social traffic doesn’t pay. In 2007, I used about a trillion hours of my time trying to hit big Diggs and Stumbles. It wasn’t until 2008 that I decided to track the performance of the traffic I got from those sources. It turned into very little income.
3. People that own successful sites are regular people. I have always approached big bloggers and site owners with a lot of respect – too much respect. I assumed that I had nothing to add and for a while didn’t even try to make a splash. As it turns out, they are regular people who are motivated by the same things everyone else is motivated by. If you can add a unique perspective, there’s nothing they would like more than to publish one of your articles, on their site.
4. Google isn’t that complicated. They look for evidence that your site has respect from other sites, and they do this by looking at links. Your ability to get traffic from Google is a simple combination of the content you produce (the things you put up on your site) and people’s reaction to that content (the links pointed at your content).
5. Volume matters in a huge way. After I started to focus a LOT more on how much work I got done in a day, my results started to explode. Having more content always matters. This might mean you need to set up more sites or it might mean that you need to expand the ones you already have.
6. Outsourcing is also king. I’m pretty amazed at this point that I was able to make as much as I did in 2007 and 2008 without oursourcing. Frankly a lot of the work that needs to be done is really monotonous and it takes a ton of time. 2009 was the year that I started to focus hard on outsourcing and it’s no coincidence that I made many times more dollar bills than I had every made before.
7. Thinking doesn’t pay nearly as much as we wish it would. I have learned a lot about myself in the last few years and I’ve figured out that I’m a dreamer – that can be good or bad. I think big but I can waste a lot of time thinking. I’ve had to learn how to execute and I can tell you that it was hard for me. I’m still not as good at it as I need to be. Execution is crucial, much more crucial than ideas.