Anyone who places advertisements on their pages should set the links contained therein to "nofollow". This way, the link does not affect the link popularity of the target page. Another aspect is this: advertisements are not part of the actual content. Imagine you run a website about shoes and an advertisement for travel offers is displayed. If the link is set to "follow", it could confuse search engines in terms of the topic when it comes to outgoing links from your page.
links in comments
Anyone who offers a comment function, a guest book or a forum on their website should always keep an eye on their users' contributions. This also applies to links posted by users. If the link is relevant to rcs data philippines the topic, it can usually be classified as harmless. However, if it seems artificial and does not really fit the topic, you should delete it or - if you are not sure - at least set it to "nofollow".
Incoming Links and Disavow
Often, website operators look critically not only at outgoing links, but also at incoming links. For a while, it was a risk if "dirty" links pointed to your own pages, for example links from porn and casino sites and from sites that deliberately spread malware. As a result, it was not uncommon for such links to be placed on your own pages, presumably by competitors. Today, these links are generally ignored when calculating rankings. The "Disavow Tool" in the Search Console can be used to downgrade harmful and questionable links. But even this is now discouraged unless a penalty ("manual measure") is imposed against you. You can still react yourself. Downgrading links without a penalty means losing their link power, even if it is very weak. An inferior link is still a link.
Conclusion
Anyone who uses the Internet, publishes their own content and occasionally places a link does not need to worry too much. Anyone who frequently places links or wants to deal with this topic in detail is better off finding out more about it. In summary, it can be said that it is better to avoid unnatural links. Links should primarily be of benefit to human visitors to the site.