What is no-follow?

No-follow is a value that can be assigned to the "rel" attribute of an HTML link to indicate that search engines should not follow the link or carry over the link value in their ranking algorithms. In other words, when a link is marked as "no-follow," it tells search engines such as Google, "Pay no attention to this link when it comes to link-related ranking factors."

Why should you use no-follow?

Using the no-follow value can be useful and even necessary in certain circumstances. Here are some reasons why:

1. Unpaid or untrusted links: Suppose you have a blog and someone posts a comment with a link to their website. Since you can't control whether this link is quality or relevant, you may decide to automatically mark all comment links as no-follow. This protects your site from possible negative SEO effects that can result from low-quality links.
2. Paid links: If you have links on your site that are paid (such as ads or sponsored content), Google recommends marking these links as no-follow. This is to prevent companies from paying for links to artificially increase their search engine rankings.
3. Temporary links: In some cases, you may want to post a link but do not want it to have much of an impact on search engines, such as if it is a temporary promotion or event.

How does no-follow work in practice?

Actually setting a link as no-follow is quite simple. This is done by adjusting the "rel" attribute of the link tag in your website's HTML code.

For example:
A regular link looks like this in HTML: <a href="https://voorbeeldsite.nl">Link to Sample Site</a>.

To make this link no-follow, add the "rel" attribute with the value "nofollow," as here: <a href="https://voorbeeldsite.nl" rel="nofollow">Link to Sample Site</a>

Once this is done, when search engines crawl your site, they will recognize the instruction and treat the link accordingly.

It is important to note that although the no-follow value indicates that search engines should not "follow" the link in terms of link value transfer, they can still crawl the link. That means they can visit the link's destination, but they will not use the link's presence as a "vote" or recommendation from one site to another in their ranking process.

In conclusion, the no-follow attribute is an essential tool for Web site owners and SEO professionals. It helps them determine how they want search engines to handle certain links on their site, giving them more control over their link profile and how it affects their SEO.