I want to write sci-fi and I love science fiction technologies. However I know you can trademark a name like Star Wars did with droid. Yet, speaking of Star Wars, Larry Niven’s Ringworld is trademarked but The Book of Boba Fett called their ringworld the Glavis Ringworld. Did they had to get permission from Niven?
Also if I make up a sci-fi tech or science term that appears in another work of fiction; do I get in trouble?
Names are not generally something that can be copyrighted. Larry Niven doesn't own a copyright to the term "Ringword" but to the artistic work of a story with the title of "Ringworld". Thus, The Book of Bobba Fett can have action that takes place on a ringworld (the structure) because aside from the two works having a setting of the same type of megastructure because they share little else in common (Having never read Ringworld, I won't begin to comment, suffice to say my understanding is that they discovered an abandoned one while the Star Wars one is populated and nobody seems to question it's origins, nor do said origins matter to the plot.).
A trademark is protection of a brand and includes protections for a combination of works packaged together (In our example, a Trademark would protect the manuscript of the book, the cover art, the title, the title's font, and other items used to distinguish a product to a consumer. You commit copyright infringement by selling a story that uses Boba Fett as a character without the owners of Star Wars saying you can do it. Trademark infringement is if you try to sell things in such a way as to trick consumers into thinking you are selling an official Star Wars product.
That said, because copyright does not protect one concept from use of others, such that Star Trek: Deep Space Nine and Babylon 5 could exist as contemporaneous works despite both dealing with people who lived and worked on a space station with a primary mission of diplomatic outreach, waring factions of aliens that were likened to gods and demons in the religions of more primitive races, a lead character that was closely tied to a major figure in an alien religion's belief systems, they didn't infringe on each other (though the fandoms of both claimed one was ripping off the other. It helps that despite the synopsis of the plots being similar, the actual stories take different paths. For example for the humans who were religiously important to alien faiths, in Deep Space 9, Sisko was declared to be The Emissary of the Prophets (the gods of the Bajoran religion) and as such was seen as a spokes person for the Prophets, and largely was uncomfortable with the faithful's reverence for him. Here the position was important, but Sisko isn't the sole Emissary, just the latest (and they are succeeded rather they are identified by religious leaders when discovered and the when the Prophets require an Emissary to assist them.). In Babylon V, Sinclair is discovered by the Mimbari to have a "Mimbari Soul", specifically the soul of Valen, the founder of their religion. Unlike an Emissary, which is a recurrent role, the religion has no strong "Second Coming" mythology regarding Valen, and they certainly never suspected that humans could be re-incarnated Mimbari. Sinclair's significance isn't shared with the public writ large (Sinclair doesn't find out for some time) while the leadership contemplate the ramifications of a second coming of Valen in the form of an alien (to them). As it turns out Sinclair isn't a second coming, but rather Valen is a time displaced Sinclair who gives the Mimbari the teachings that would form the religion, creating a stable time loop.
The term "Droids" is similarly not inherent to Star Wars. It's short for "Android" which typically refers to an artificial automaton with a humanoid shape (derrived from the greek "Andr-" meaining "Man" and "-oid" being like.). Notably, the term was distinct from "robot" in that robot is always mechanical where as not all androids are mechanical. George Lucas instead used Droid to mean "Robot" regardless of whether they looked human like or like a Trash Can. And the term was used by other works prior to Star Wars such as Phillip K. Dick's 1968 novel "Do Androids Dream of Electric Sheep" which predated Star Wars by almost a decade, as well as the character of Lt. Cmdr Data from "Star Trek: The Next Generation" who exclusively was called an Android and on occasion the show did refer to him as simply a "droid" (I recall one specific instance of it, where a character was making a joke which required the phrase "a droid" in it's word play). Hell, this means that Data and C-3P0 are both droids strongly associated with the color gold... though C-3P0 is a golden colored metal plated human shaped robot with a pessimistic attitude that causes him constant worry and Data is a robot with externa materials designed to mimic the feel of a biological human that is incapable of any emotional responses... and wears a gold shirt (dialog suggests that material used for his skin, irises and hair contains trace amounts of gold, which accounts for pale inhuman look the make-up artist used for the character... but compared to C-3P0, Data can pass for a human in a deception operation.).
If you inadvertently infringe on a trademark, and the rightful trademark owner finds out, you will likely first get a Cease and Desist letter warning you to stop using their trademark. I don't think their first recourse would be suing your pants off. (But I am not a lawyer, and I don't know how desirable your pants are.)
The purpose of a trademark is to identify goods/services from a particular source and distinguish them from others. So to keep with the spirit of that, you should avoid doing things that would lead people to confuse your work as being by, or endorse by, other trademark holders (when they're not).
Writing a story that has a ringworld in it, but isn't in any way presented as a Ringworld novel, would (in my lay opinion) not be likely to infringe on a Ringworld trademark (if one applied). Such a trademark would protect the Ringworld universe, but not the idea of a ring shaped world that anyone would reasonably call a ringworld. This should apply to most sci-fi/science concepts.
It is also important to keep in mind that trademarks apply to particular goods and services. The trademark of someone that only sells shoes isn't an impediment for someone that only sells fruit or other unrelated goods and services. It only becomes an issue when you're trading in the same area. That's why the computer company Apple and the music label Apple have had a few scuffles over the years when the former got into the latter's territory.
To avoid infringing on someone's trademark, you can look them up them in a trademark database such as https://branddb.wipo.int/branddb/en/
For example, if you look up "Ringworld", there are a few active records, but none are owned by Larry Niven, and the most relevant one seems to only apply to movies and television series. If you look up "Droid", the ones owned by Lucasfilm Ltd. seem (to me) to apply mostly to merchandising.
So, in summary, I wouldn't worry about it too much, as long as you avoid presenting your story as being part of a known fictional universe.
