A Web crawler may use PageRank as one of a number of importance metrics it uses to determine which URL to visit during a crawl of the web. One of the early working papers that were used in the creation of Google is Efficient crawling through URL ordering, which discusses the use of a number of different importance metrics to determine how deeply, and how much of a site Google will crawl. PageRank is presented as one of a number of these importance metrics, though there are others listed such as the number of inbound and outbound links for a URL, and the distance from the root directory on a site to the URL.
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!)
Another reason is that if you're using an image as a link, the alt text for that image will be treated similarly to the anchor text of a text link. However, we don't recommend using too many images for links in your site's navigation when text links could serve the same purpose. Lastly, optimizing your image filenames and alt text makes it easier for image search projects like Google Image Search to better understand your images.
Search queries—the words that users type into the search box—carry extraordinary value. Experience has shown that search engine traffic can make (or break) an organization's success. Targeted traffic to a website can provide publicity, revenue, and exposure like no other channel of marketing. Investing in SEO can have an exceptional rate of return compared to other types of marketing and promotion.
I’ve never been particularly enamoured with nofollow, mainly because it breaks the “do it for humans” rule in a way that other robots standards do not. With other standards (e.g. robots.txt, robots meta tag), the emphasis has been on crawling and indexing; not ranking. And those other standards also strike a balance between what’s good for the publisher and what’s good for the search engine; whereas with nofollow, the effort has been placed on the publisher with most of the benefit enjoyed by the search engine.
Totally agree — more does not always equal better. Google takes a sort of ‘Birds of a Feather’ approach when analyzing inbound links, so it’s really all about associating yourself (via inbound links) with websites Google deems high quality and trustworthy so that Google deems YOUR web page high quality and trustworthy. As you mentioned, trying to cut corners, buy links, do one-for-one trades, or otherwise game/manipulate the system never works. The algorithm is too smart.
As for the use of nofollow as a way to keep pages that shouldn’t be indexed out of Google (as with your feed example) is terrible advice. Your use of it on your feed link does nothing. If anyone links to your feed without nofollow, then it’s going to get indexed. Things that shouldn’t be indexed need to use either robots.txt or meta robots blocking. Nofollow on links to those items isn’t a solution.
Online marketing, also called digital marketing, is the process of using the web and internet-connected services to promote your business and website. There are a number of disciplines within online marketing. Some of these include social media, search engine marketing (SEM), search engine optimization (SEO), email marketing, online advertising and mobile advertising.