A website with not much link juice should not be sending them out to places not beneficial to it and much more so if you are already an established website with a good reputation to be taken care of. That is where nofollow attribute could help keep the valuable link juice stay within the site unless intended otherwise.
In simplest terms, "nofollow" means to, well… not follow. If used in the site, this tells webmasters which pages or links should not be crawled by search engines. A concept introduced by Matt Cutts, former head of the web spam team at Google, and Jason Shellen, founding product manager of Google Reader in 2005.
However, still be guided with Google's clarification:
“The target pages may still appear in our index if other sites link to them without using nofollow, or if the URLs are submitted to Google in a Sitemap.” – Search Console Help
Advantages of using Nofollow links:
- Natural looking site
A well-balanced mix of dofollow and nofollow links could deem your site as natural looking. The idea is to not get on the bad side of Google once an algorithm update takes place. It’s like precautionary measures before disaster hits.
- Help in spam-fighting
Since you wanted to encourage interactions on your site through the comment section, be sure to make the inserted links be nofollow because any content coming from a user side can be a spam.
To make sense of it all, here's the types of nofollow you could use in the website
Types of Nofollow
- Robots Meta Tag
<meta name="robots" content="nofollow" />
Before the introduction of nofollowing individual links, page-level meta tag was included to instruct search engines to avoid following outgoing links found in the page.
However, this solution became ineffective due to the effort needed to be allotted. And so another solution was created,
- Link Attribute
<a href="signin.php" rel="nofollow">sign in</a>
Since there are still links in a page that need to be followed, this solution comes in handy; the idea is to only add a nofollow attribute to specific links you do not wish to be crawled. It's like having the authority on who gets the juices and who don't.
Now that you know what is what, time to put it to good use. Here is a list of outgoing links you should be adding nofollow attributes to avoid drying up your juices.
Types of Outgoing Links to Nofollow
Paid links could either be a paid review or a product link. In short, to place that link to a certain site, monetary or exchange of goods were given as token.
Placement of paid links are required by Google to be nofollow else, you run the risk of penalization.
Guest Post Links
Guest postings used to be a respectable and unbiased way of informing, however even as the trend started as authentic, more and more people will rig the system for their advantage. Covering up a paid link into a guest post could penalize you severely.
Source links in widgets and images
Image sources of attached images should be nofollow as well as embedded links found on widgets.
In this way, Google will not deem the site as link schemed.
Social Media Buttons
Widely popularized social media platforms are Facebook, twitter, Instagram, and so on.
You don't need to send out link juices to these already high-ranking websites. Best to keep it to yourself or do some smart internal linking instead.
Additional note: Other links to integrate a nofollow attribute to are noindexed links and admin pages since they should not be crawled by Google. Same goes for attached links on comments.
As Google strive to make the web a better place, we as SEO professionals should take part of the beneficial change one proper usage of nofollow link at a time.