NoFollow Links
Google introduced the so-called NoFollow attribute in 2005. The Google employees Matt Cutts and Jason Shellan are responsible for the idea behind it. NoFollow basically intends that all links that are not of an editorial nature are clearly marked. Editorial links are usually found within an informational article or refer to such an article.
NoFollow should prevent masses of links from being set in blog comments or guest books, or that such links, which are often generated automatically and only for SEO reasons, have an influence on the ranking. In the past, it was de facto possible to quickly gain advantages in terms of positioning in the SERPs simply by creating a large number of links from pages with a high PageRank.
In terms of SEO content, NoFollow links are said to have a positive effect on your own link juice. This should give you the opportunity to exclude pages that are less important for the search engine, such as the imprint or registration pages, from the index. The common assumption is that this increases the link power on other important pages. In practice, however, it has been shown that such measures do not bring any benefits. On the contrary: Google itself points out in the help section of the Search Console that it would be more effective to use resources for user-friendly navigation and URL structures than to try to influence the crawling process with the NoFollow attribute.
So NoFollow links do not affect the SEO or the SEO content in which they are placed, correct? The quick answer is: No, NoFollow links do have a certain SEO relevance. In the SEO scene, this question has long been hotly debated and answered quite differently. Some are of the opinion that a link profile with a very high proportion of NoFollow links would have no influence at all, because no PageRank is passed on and corresponding links could therefore have no effect on the ranking. Others, however, are convinced that NoFollow links have various effects and that too many of them in particular can have a negative influence on the ranking. In fact, there is not even agreement on the point that a NoFollow tag really does not transmit any signals or that it actually prevents Google from following a link.
It is clear, however, that NoFollow links are part of a natural link profile. In this respect, it can certainly be interpreted that the absence of such links can negatively influence the ranking in a certain way. However, the presence or absence of such links will never cause a massive ranking influence.
Broken-Links
Broken links are references or links that lead to a destination on the Internet that can no longer be reached. The link target can be a page, but also a file or another download. Normally, when users click on a broken link, they receive an error message with the status “404 Not Found” or “410 Gone”. If a website has a lot of broken links, this can lead to a negative evaluation on the part of the search engines and a devaluation in the SERPs. Broken links are also called “dead links”, “broken links” or “missing links”.
The bots of the search engines as well as human visitors appreciate it when the content of a website is up-to-date and when, for example, they find exactly the information they are looking for after following a link in the SERPs or on another page that is ideally on the same topic. In this respect, it should be noted that what is advantageous or not advantageous for users is also advantageous or not advantageous for bots.
If there is an accumulation of broken links on or to a website, on the one hand the user experience is damaged, which in turn is evaluated negatively by Google and Co. On the other hand, they also make crawling more difficult, which means that they can actually be attributed a direct negative SEO influence.
If broken links on a website are not removed, the crawlers follow them again with every visit. This means that target pages that have long since disappeared may remain in a search engine’s index for months or even years. If your customers click on a corresponding entry of your company website in the SERPs, the lack of the expected information may even have a negative effect on the competence of your entire brand.
Broken links must therefore be detected and eliminated. Of course, you can find broken links on your own website manually. However, this is always associated with an increased risk that various links will simply be overlooked. It is safer to use an appropriate tool. There is a huge selection here, and even when using a CMS such as WordPress, you can benefit from numerous applicable plug-ins that reliably detect broken links.
Optimally, however, you should not allow broken links to occur in the first place. A common method to exclude broken links in the SERPs is to provide the search engines with an XML sitemap with all available correctly functioning subpages of your domain. Optionally, you can also submit a separate sitemap that only applies to images. This requires, for example, a Google Webmaster Tools account.
In addition, make sure – especially in the case of major changes or a relaunch – that all subpages of a project are basically accessible and that outgoing links also lead to a destination.
It is very dangerous to change the storage locations for files, as it is not uncommon for many links to be connected to them. In this case, all links referring to the downloads must be adapted accordingly. If URLs of a domain change, it is recommended to first create a connection from the old to the new target page via the .htaccess file using 301 redirect. This way, visitors are referred to the new content almost without noticing.