Mega-sites, like have tens or hundreds of editors writing new content – i.e. new pages - all day long! Each one of those pages has rich, worthwile content of its own and a link back to its parent or the home page! That’s why the Home page Toolbar PR of these sites is 9/10 and the rest of us just get pushed lower and lower by comparison…
You can confer some of your site's reputation to another site when your site links to it. Sometimes users can take advantage of this by adding links to their own site in your comment sections or message boards. Or sometimes you might mention a site in a negative way and don't want to confer any of your reputation upon it. For example, imagine that you're writing a blog post on the topic of comment spamming and you want to call out a site that recently comment spammed your blog. You want to warn others of the site, so you include the link to it in your content; however, you certainly don't want to give the site some of your reputation from your link. This would be a good time to use nofollow.
Well, to make things worse, website owners quickly realized they could exploit this weakness by resorting to “keyword stuffing,” a practice that simply involved creating websites with massive lists of keywords and making money off of the ad revenue they generated. This made search engines largely worthless, and weakened the usefulness of the Internet as a whole. How could this problem be fixed?
Backlinks are important for both search engines and end users. For the search engines, it helps them determine how authoritative and relevant your site is on the topic that you rank for. Furthermore, backlinks to your website are a signal to search engines that other external websites are endorsing your content. If many sites link to the same webpage or website, search engines can interpret that content is worth linking to, and therefore also worth ranking higher on a SERP (search engine results page). For many years, the quantity of backlinks was an indicator of a page’s popularity. But today algorithms like Google's Penguin update, were created to help with other ranking factors; pages are ranked higher based on the quality of the links that they are getting from external sites and less on quantity.
According to the U.S. Commerce Department, consumers spent $453.46 billion on the web for retail purchases in 2017, a 16.0% increase compared with $390.99 billion in 2016. That’s the highest growth rate since 2011, when online sales grew 17.5% over 2010. Forrester predicts that online sales will account for 17% of all US retail sales by 2022. And digital advertising is also growing strongly; According to Strategy Analytics, in 2017 digital advertising was up 12%, accounting for approximately 38% of overall spending on advertising, or $207.44 billion.
If you’re just getting started with SEO, you’re likely to hear a lot about “backlinks,” “external and internal links,” or “link building.” After all, backlinks are an important SEO ranking factor for SEO success, but as a newbie, you may be wondering: what are backlinks? SEO changes all the time — do backlinks still matter? Well, wonder no more. Say hello to your definitive guide to backlinks and their significance in SEO.
Page Structure - The third core component of SEO is page structure. Because web pages are written in HTML, how the HTML code is structured can impact a search engine’s ability to evaluate a page. Including relevant keywords in the title, URL, and headers of the page and making sure that a site is crawlable are actions that site owners can take to improve the SEO of their site.
So, for example, a short-tail keyphrase might be “Logo design”. Putting that into Google will get you an awful lot of hits. There’s a lot of competition for that phrase, and it’s not particularly useful for your business, either. There are no buying signals in the phrase – so many people will use this phrase to learn about logo design or to examine other aspects of logo design work. 

Yep, please change things to stop keyword stuffing. Change them to stop cloaking. Definately change them to stop buying links that try to game Google. But, telling search engines to not give weight (that I control) to pages that are not what my site is about or are not really relevant. No way. This is logical stuff here. Maybe too logical. I think deep down you know this Matt too.

By 2004, search engines had incorporated a wide range of undisclosed factors in their ranking algorithms to reduce the impact of link manipulation. In June 2007, The New York Times' Saul Hansell stated Google ranks sites using more than 200 different signals.[25] The leading search engines, Google, Bing, and Yahoo, do not disclose the algorithms they use to rank pages. Some SEO practitioners have studied different approaches to search engine optimization, and have shared their personal opinions.[26] Patents related to search engines can provide information to better understand search engines.[27] In 2005, Google began personalizing search results for each user. Depending on their history of previous searches, Google crafted results for logged in users.[28]

Also, by means of the iterative calculation, the sum of all pages' PageRanks still converges to the total number of web pages. So the average PageRank of a web page is 1. The minimum PageRank of a page is given by (1-d). Therefore, there is a maximum PageRank for a page which is given by dN+(1-d), where N is total number of web pages. This maximum can theoretically occur, if all web pages solely link to one page, and this page also solely links to itself.
Matt, this is an excellent summary. I finally got around to reading “The Search” by John Battelle and it was very enlightening to understand much of the academia behind what led to the creation of Backrub.. er Google.Looking at how many times the project was almost shutdown due to bandwidth consumption (> 50% of what the university could offer at times) as well as webmasters being concerned that their pages would be stolen and recreated. It’s so interesting to see that issues we see today are some of the same ones that Larry and Sergey were dealing with back then. As always, thanks for the great read Matt!
Here’s my take on the whole pagerank sculpting situation. As I understand it, the basic idea is that you can increase your rankings in Google by channeling the page rank of your pages to the pages you want ranked. This used be done with the use of the ‘no folow’ tag. That said, things have changed, and Google has come out and said that the way ‘no follow’ use to work has changed. In short, using ‘no follow’ to channel that page rank juice is no longer as effective as it once was.

It's clear that online marketing is no simple task. And the reason why we've landed in this world of "expert" internet marketers who are constantly cheerleading their offers to help us reach visibility and penetrate the masses is because of the layer of obscurity that's been afforded to us in part thanks to one key player: Google. Google's shrouded algorithms that cloud over 200+ ranking factors in a simple and easy-to-use interface has confounded businesses for well over a decade now.
First of all, it’s necessary to sort out what a backlink is. There is no need to explain everything in detail. The main thing to understand is what it is for and how it works. A backlink is a kind of Internet manipulator. It links one particular site with other external websites which contain links to this site. In other words, when you visit external sites they will lead you to that particular site.

Most people need to take a step back and understand where money is even coming from on the web. Sharpe says that, when asked, most individuals don't actually even know how money is being made on a high level. How does Facebook generate its revenues? How about Google? How do high-trafficked blogs become so popular and how do they generate money from all of that traffic? Is there one way or many?
Digital marketing is probably the fastest-changing marketing field out there: New tools are being built, more platforms emerge and more channels need to be included into your marketing plan. How not to get overwhelmed while staying on top of the latest marketing trends? Here are a few tools that help you scale and automate some parts of your marketing routine making you a more productive and empowered marketer: Tools to Semi-Automate Marketing Tasks 1.
If you want to concentrate the PR into one, or a few, pages then hierarchical linking will do that. If you want to average out the PR amongst the pages then "fully meshing" the site (lots of evenly distributed links) will do that - examples 5, 6, and 7 in my above. (NB. this is where Ridings’ goes wrong, in his MiniRank model feedback loops will increase PR - indefinitely!)
The first component of Google's trust has to do with age. Age is more than a number. But it's not just the age when you first registered your website. The indexed age has to do with two factors: i) the date that Google originally found your website, and; ii) what happened between the time that Google found your website and the present moment in time.

There is much discussion in these last few months about reciprocal linking. In the last Google update, reciprocal links were one of the targets of the search engine's latest filter. Many webmasters had agreed upon reciprocal link exchanges, in order to boost their site's rankings with the sheer number of inbound links. In a link exchange, one webmaster places a link on his website that points to another webmasters website, and vice versa. Many of these links were simply not relevant, and were just discounted. So while the irrelevant inbound link was ignored, the outbound links still got counted, diluting the relevancy score of many websites. This caused a great many websites to drop off the Google map.
To cease opportunity, the firm should summarize their current customers' personas and purchase journey from this they are able to deduce their digital marketing capability. This means they need to form a clear picture of where they are currently and how many resources they can allocate for their digital marketing strategy i.e. labour, time etc. By summarizing the purchase journey, they can also recognise gaps and growth for future marketing opportunities that will either meet objectives or propose new objectives and increase profit.

I think that removing the link to the sitemap shouldn’t be a big problem for the navigation, but I wonder what happens with the disclaimer and the contact page? If nofollow doesn’t sink the linked page, how can we tell the search engine that these are not content pages. For some websites these are some of the most linked pages. And yes for some the contact page is worth gaining rank, but for my website is not.