“Fanservice” is loosely defined as events and characters being added to or changed in media strictly for the audience’s entertainment that does not usually have much impact on the story. It is usually shown off in a suggestive or sexual nature.
Due to cultural differences and the fact that fanservice originated there, most of the suggestive style of fanservice is in Japanese media such as manga and anime , with one of the most infamous examples in my experience being the anime “That Time I Got Reincarnated as a Slime.” Risqué character designs, constant excuses to rip off top layers of clothing, and Demon Lord Milim Nava, are just some of the rampant ways this one anime includes a level of fanservice in it.
Of course, Japanese media is not the only media that includes suggestive fanservice. One example of American media including this is “Star Wars: Return of the Jedi” when Princess Leia had to wear very skimpy clothing when enslaved by Jabba the Hutt. I find this form of fanservice disgusting, especially when it is used in media with characters who are minors or simply look young.
Now, not all fanservice is of a suggestive nature, with most fanservice in Western media being references to other media or in-world memorials to deceased actors, such as when Disney tied in the death of actor Cameron Boyce into the story of their “Descendants” movie series in “Descendants: The Rise of Red.” This type of fanservice can also come in advertising, such as when some advertisements for “Back to the Future 2” included the famous quote said by Doc in the cliffhanger of the first movie: “Roads? Where we’re going, we don’t need roads.”
All in all, fanservice is a tool that can be used in many ways, from playing to sexual fantasies to honoring the dead, and it is really up to the creator of a series to choose how they use it. I would personally hope that they choose to use it in a powerful and meaningful way.
