A pingback is a notification that is sent to your blog when another blog linked to it via a permalink. It is a signal which is transmitted automatically using the XML-RPC protocol.
The terms pingback and trackback are often used interchangeably, but a pingback is an automated trackback with the difference that pingbacks are merely a signal and does not, as is the case with trackbacks, appear in the comments section below the blog post and may have content relevance.
Technically, both terms refer to a notification which are automatically sent to your blog if it got linked to. However, trackbacks use the HTTP post method and not an XML protocol. Pingbacks were introduced in order to achieve a certain level of authenticity because trackbacks can be processed by the recipient, so that they no longer correspond to the original format and only appear as a comment without URL.
Simultaneously trackbacks can be misused as spam if they include a URL and therefore a backlink to a unrelated external website. Pingbacks are meant to provide a solution to the owner of the blog which was linked to, because sometimes such a link is not desirable.
The principle of pingbacks is relatively simple. A blog post is published on website A, which contains a link to another resource B. Resource B is then notified that a link has been set to this resource. Usually this happens within the CMS and e-mail notifications are an option as well. The pingback includes a URL and an excerpt of the text which was linked from. In CM systems such as WordPress, pingbacks can be approved, deleted or treated as spam. However, they must always be allowed in the used theme or in the basic settings.
Even within a blog, pingbacks can be sent. If an internal link is set, the owner and in this case probably the author will receive a pingback. These are so-called self-pings, which can be disabled, however.
The original benefit of pingbacks was that bloggers were automatically informed through pingbacks about any links and therefore to some extent about the impact or scope of their blog posts.
Pingbacks have different importance for search engine optimization. Once a link has been set to a blog, the owner of the blog receives a message. With this kind of “early warning system” bloggers can avoid getting links from a bad neighborhood or the content from which the link originated not being relevant to their topic. Thus pingbacks fulfill a dual function. As a blogger, you can get attention from other websites by using links.
At the same time, pingbacks can be used as a control function, when other blogs link to your site. In the comments of your posts, you can delete or deactivate the respective pingbacks. For a long time, pingbacks and even more so trackbacks were used for massive backlink building. For each new post, SEOs would send many trackbacks to topic-relevant websites which then had the post URL in their comments. Such links were not marked as a nofollow link for a long time and each trackback therefore also produced link juice. This often posed a problem to bloggers of having to pass on a lot of link power through trackbacks. Thus, the pingback / trackback system was no longer being used as a useful information system, but abused as a backlink generator by spammers. For this reason, many bloggers see pingbacks today as spam and disable the corresponding function.
Pingbacks are, however, still helpful as a notification feature, especially to avoid spam.