Too many outbound links on a website can deplete a site’s own PageRank (the importance Google assigns to a page based on an automatic calculation that factors in the link structure of the web and many other variables). However, this may be more of a relative than an absolute statement; there are ways to externally link to relevant websites without reducing the importance of your own website.

In its simplest form, PageRank can be explained with this formula:

PR(A)= PR(B) + PR(C) + PR(D)

From the formula above, the sum of the PageRank of pages B, C and D is awarded to page A because all of their links are pointing to A. Basically, pages B, C and D are passing on some of their own “link juice” to Page A.

PageRank is assigned on a page by page basis in that the more outbound links one has on a particular page, the PageRank of the page itself is affected. An intelligent strategy is to create a page on the site that includes a collection of links to websites that your users will find helpful. This is a good idea as externally linking from an internal page on your site as opposed to the homepage will not have that much of an affect on the site as a whole. The homepage typically has the highest PageRank by virtue of the links pointing to it. That PageRank from the homepage flows to the internal pages on the site. So, to keep that healthy internal link structure intact, we’d essentially want to have outbound links coming from a lower level page.

However, all of this can be completely avoided with the nofollow attribute. A few years ago, Google put into action the nofollow attribute so webmasters could link to other websites without losing their own “link juice”. This is useful if a webmaster wants to provide links to other quality websites for their users and not lose their own PageRank status.

It has been the case for many years that the most optimal way to handle defunct pages on your website was to have the server return a 404 (Not found) HTTP status code. Google has just recently confirmed, however, that they now consider the 410 (Gone) response code to be a stronger signal that the page has gone away for good.

HTTP response codes are designed for both users and search engine spiders to give them information about what has happened to a site’s page. When a user stumbles upon a page that is issuing a 404 or 410 response code, they will sometimes see the message “Page Not Found”. So, if both of these response codes yield the same response for the user, what is the benefit of using one over the other?

According to Google, when a page issues a 404 header response, it may sometimes still revisit the page to ensure that it is truly defunct. What this means in terms of indexing is anyone’s guess, but using the 410 response code will at least ensure that Google will never go back to that page again and get to the more important pages on the website, thus facilitating crawlability.

The 410 response code should be used when there is no other option, meaning that this page cannot be redirected to a similar or corresponding page. So if you’re absolutely sure that a page no longer exists and will never exist again, using a 410 would likely be a good thing. It’s probably not worth the time or effort rewriting a server by changing the 404 to a 410, but using the 410 in the future will at least give Google the stronger message that they are looking for.

Determining the placement of certain pages of ones site can be a challenging task for any webmaster. Many people, especially if you are new to developing websites, are perplexed by the question of whether or not to go the subdomain route (blog.example.com) or the directory route (www.example.com/blog).

The general consensus is that subdomains are usually reserved for pages that aren’t completely associated with the general theme of the site. Google, for example has http://maps.goolge.com, http://books.google.com/ and http://blogsearch.google.com/. From an SEO perspective, it has been said that “link juice” will not necessarily flow from the main domain to pages within a subdomain. This has proven not to be the case; however, as some webmasters have seen pages within their subdomains garner the same link value as their main domain.

The real question, though, is whether there is any kind of duplicate content on the subdomain. There is a trap that some webmasters fall into where, because they haven’t set up their site architecture in a logical manner, that some pages of their subdomain duplicate pages from their main domain. While this will rarely incur some kind of penalty within the search engines, it may prevent the search engines from crawling the most important pages on the website given the “crawler caps” the search engine spiders have in place. Matt Cutts of Google has said that for newer webmasters, the subdirectory structure is the way to go until you are more confident with your site’s architecture. I tend to agree.