It’s obvious that if you are writing a fantasy or sci-fi, you have to actually build the world your character lives in. But what a lot of people, especially non-writers don’t know is that with every book, you have to build a world.
Even if you use a real city, your characters need to interact with other characters, and that means creating places where they live, work, socialize, and/or get educated.
If I wrote a novel about a cop (and I have), or an FBI agent (and I have), I had to give them friends who lived in houses, apartments, etc., who had jobs, and families and all the things real people have in their lives. I actually created the town, the sheriff’s dept, the night club, the local donut shop, even the park. I drew a map with street names and stop signs. I created county and city buildings, two casinos and a bayou. I used a real river and two real cities as land marks so readers could get the general idea of the town’s location, but was not specific enough for them to find it on a map.
This is a fun part of writing for me. To decide what the population is, what the crime rate is, and whether the people are generally well educated and upper class, or if the inhabitants represent a cross-section of class, affluency, and race. This is what makes the place real.
In Ultimate Justice, A Trey Fontaine Mystery, there is a stain on the antique wall paper in the office/living room of Trey’s mother. I created that stain, but Trey made it.
In the sheriff’s dept bullpen where the detectives congregate and have desks, there are two desks that are touching, so the two detectives face each other. Is that a good thing? Is that how you would do it?
Writing is about creating. And writers need to remember to create the whole picture. Not just the character, but the setting, is vital to the suspension of disbelief.