A search engine considers the content of the sites to determine the QUALITY of a link. When inbound links to your site come from other sites, and those sites have content related to your site, these inbound links are considered more relevant to your site. If inbound links are found on sites with unrelated content, they are considered less relevant. The higher the relevance of inbound links, the greater their quality.

We must be careful with our reciprocal links. There is a Google patent in the works that will deal with not only the popularity of the sites being linked to, but also how trustworthy a site is that you link to from your own website. This will mean that you could get into trouble with the search engine just for linking to a bad apple. We could begin preparing for this future change in the search engine algorithm by being choosier with which we exchange links right now. By choosing only relevant sites to link with, and sites that don't have tons of outbound links on a page, or sites that don't practice black-hat SEO techniques, we will have a better chance that our reciprocal links won't be discounted.
Keyword analysis. From nomination, further identify a targeted list of key­words and phrases. Review competitive lists and other pertinent industry sources. Use your preliminary list to determine an indicative number of recent search engine queries and how many websites are competing for each key­word. Prioritize keywords and phrases, plurals, singulars and misspellings. (If search users commonly misspell a keyword, you should identify and use it). Please note that Google will try to correct the term when searching, so use this with care.
Moreover, the PageRank mechanism is entirely general, so it can applied to any graph or network in any field. Currently, the PR formula is used in bibliometrics, social and information network analysis, and for link prediction and recommendation. It's even used for system analysis of road networks, as well as biology, chemistry, neuroscience, and physics.
Search engines are a great way to find business online. They offer “passive” marketing approaches for those who don’t want to get into “active marketing”. SEO can be incredibly powerful, but it’s often too slow for someone who needs clients today (rather than in six months’ time) to be a good marketing strategy when you launch your business. It’s cheap (though it’s not free – your time is worth money too), and it can be very effective in the medium to long term.
If you are going to use SEM, you must build the costs of using this form of marketing into your cash-flow forecasts and the prices you’re charging for your work. Spending $3,000 a month on Adwords to land $20,000 of business is eminently sensible in most cases. Spending $3,000 a month to land $3,500 of business, on the other hand, is likely to be a disaster for your business’s ability to trade effectively in the long term.
Well, it seems that what this article says, is that the purpose of the no-follow link is to take the motivation away from spammers to post spam comments for the purpose of the link and the associated page rank flow; that the purpose of no-follow was never to provide a means to control where a page’s pagerank flow is directed. It doesn’t seem that shocking to me folks.
If you’re a blogger (or a blog reader), you’re painfully familiar with people who try to raise their own websites’ search engine rankings by submitting linked blog comments like “Visit my discount pharmaceuticals site.” This is called comment spam, we don’t like it either, and we’ve been testing a new tag that blocks it. From now on, when Google sees the attribute (rel=“nofollow”) on hyperlinks, those links won’t get any credit when we rank websites in our search results.
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.
However, with all of these so-called modern conveniences to life, where technology's ever-pervading presence has improved even the most basic tasks for us such as hailing a ride or ordering food or conducting any sort of commerce instantly and efficiently, many are left in the dark. While all of us have become self-professed experts at consuming content and utilizing a variety of tools freely available to search and seek out information, we're effectively drowning in a sea of digital overload.

An Internet marketing campaign is not an isolated, one-off proposal. Any company that plans on using it once is certain to continue to use it. An individual who is knowledgeable about all aspects of an Internet marketing campaign and who has strong interpersonal skills is well-suited to maintain an ongoing managerial role on a dedicated marketing team.
Cause if I do that, If I write good content, whilst my 100+ competitors link build, article market, forum comment, social bookmark, release viral videos, buy links, I’ll end up the very bottom of the pile, great content or not and really I am just as well taking my chances pulling off every sneaky trick in the book to get my site top because, everyone does it anyway and if I don’t what do have to lose?”
Non-profit corporations and political entities use Internet marketing to raise awareness about the issues they address and engage individuals in their campaigns. They strongly favor social networking platforms because they are more personal than websites and they are easy to share, increasing the “viral” word-of-mouth effect that is so prevalent in online media.
[44] Matteo Pasquinelli reckons the basis for the belief that PageRank has a social component lies in the idea of attention economy. With attention economy, value is placed on products that receive a greater amount of human attention and the results at the top of the PageRank garner a larger amount of focus then those on subsequent pages. The outcomes with the higher PageRank will therefore enter the human consciousness to a larger extent. These ideas can influence decision-making and the actions of the viewer have a direct relation to the PageRank. They possess a higher potential to attract a user's attention as their location increases the attention economy attached to the site. With this location they can receive more traffic and their online marketplace will have more purchases. The PageRank of these sites allow them to be trusted and they are able to parlay this trust into increased business.
I agree that the more facts that you provide and if you were to provide the complete algorithm, people would abuse it but if it were available to everyone, would it not almost force people to implement better site building and navigation policies and white hat seo simply because everyone would have the same tools to work with and an absolute standard to adhere to.
PageRank has been used to rank spaces or streets to predict how many people (pedestrians or vehicles) come to the individual spaces or streets.[51][52] In lexical semantics it has been used to perform Word Sense Disambiguation,[53] Semantic similarity,[54] and also to automatically rank WordNet synsets according to how strongly they possess a given semantic property, such as positivity or negativity.[55]
But I also don’t wanna lose PageRank on every comment with a link… If I can give PageRank and lose none, I wanna let the comment there, even without nofollow. But if I lose PageRank on every link, even inside original post, EVEN MORE if nofollow also takes PageRank out of me, I may just start using JavaScript or simple text without anchor for links… I definetely don’t like this idea, but I dislike even more losing PageRank on each outlink on my site. I’d just link top quality sites that I actively wanna vote for Search Engines.