Many creatives --- not only writers --- love acts of creation like worldbuilding. Because artists of all stripes of love to create anyway… it’s what we do. And once we’ve created, we want to share the fruits of our labour. Think of Tom Hanks in the film Castaway, having finally succeeded, after being shipwrecked on a deserted island and engaging in hours of backbreaking work, finally igniting a freaking giant bonfire. As he dances around the flames, celebrating his small triumph after having the universe shit all over him, he gestures to the silent stars shining above and shouts “Look what I have created! I… have… made… FIRE!” Yeah. Worldbuilding can be like that. I think acts of creation fill a basic, primal need that so many of us seem to have. In fact, that primal need is one of the few things about humanity giving me hope nowadays: that want to build and create, not just tear down and destroy.
There’s a definite art to worldbuilding; it needs to manifest in drips, not a flood. A fire hose of information in the middle of your narrative just turns readers off, so, unless you’re writing appendices that follow the end of your story, and it’s made very clear that they aren’t part of the story per se, limit the details you throw out. They should just appear as part of the landscape or a character’s actions.
Setting is part of worldbuilding. To say that setting the "when" and "where" of a story may satisfy a basic definition, but it doesn’t delve into the kind of detail authors can, probably should, and often do go into when plotting stories. After all, setting isn’t, and shouldn’t be thought of, as a static or non-moving picture. In the best stories, it’s a richly woven tapestry providing not only background for the plot itself, but can rival the plot in interest and ignite in the reader an intense desire to learn more about the world in which the story takes place.
When authors fashion the world in which their stories take place --- and J.R.R. Tolkien, creator of The Hobbit, The Lord of the Rings, and The Silmarillion is among the most famous writers ever to do so --- they engage in acts of Creation. Consider: to build a world; put landscapes upon it; fill those lands with plants and animals; people those lands; build cultures, cities, and languages --- these are all acts of Creation which can ultimately be hugely rewarding and enjoyable. I use the word "Creation" with a capital "C" quite deliberately, because, if time and care are taken in generating details like those mentioned above, the parallels between an author's acts of Creation and God's acts of Creation are very real (if not perhaps on the same scale!).
The act of creating setting and worlds for stories is a vital one and shouldn’t be dismissed as an afterthought or just a necessary nuisance, a "peg" on which to hang the "coat" of the plot. While this is true of all literature, one has only to look at some of the great fantasy works to see that this seems especially true for it. A prime example is The Hobbit, Tolkien's other best-known work taking place in Middle Earth, and which, unlike The Lord of the Rings, was written for children. The "magical" places (not necessarily in the literal sense) of so many fantasy stories really almost require a richness and depth to their settings that many other types of literature don’t strictly need in order to succeed.
Worldbuilding doesn’t belong only at the beginning, or the middle, or the end of stories. Great authors constantly give readers more information about the worlds in which their characters interact. Such detail isn’t only setting; it’s texture. Stephen King calls it chrome --- the details which take something very ordinary and lacklustre and give it glitter and interest. (And he should know.)
So build on, worldbuilders! You’ve nothing to lose, and rich, fulfilling environments to create and savour.