It's easy to see how research would be needed when writing non-fiction. You need to get your facts right. But what about fiction? You're just making stuff up, right? Well, unless you're writing some REALLY out there fantasy, that's probably not right. Even if your location is completely made up and none of your characters have ever existed, there's still things to get right. Are the laws of physics the same? Do you need to know about some particular job? Do your characters reference historical events? Even if those are made up, they must be "researched" and documented in order to ensure things remain self-consistent.
Depending on the genre, there may be quite a bit more to dig into. The novel I'm planning now takes place in a "real" place: a former crofting township that was abandoned in the 1800s. There are other townships near it that still survive, and in my book, it does, too. So I need to know the particulars of its geography, and I need to know as much as I can about these communities in the periods in which my story takes place (the last forty or so years). One structure in my story still stands, though it is now in ruins. I've been able to find lots of images of it, though, and architectural notes that let me sketch out a plausible floor plan.
There are laws, old and new, that have affected these communities and I need to know about them, too. There's the entire culture of its people, including language, dress, food, and entertainment. There's the history of why so many townships like this one have failed over the last couple hundred years (and especially the last fifty years), and what the ones that remain are doing to survive. There's all the details that one just naturally knows living in a culture and location, details my characters all know, and so I must know them, too.
Fortunately, there are lots of resources available that make this straightforward if not easy. Mapping sites provide not only the roads and terrain, but even detailed views from satellites. Almost any place has its devotees that have written about it on the web. There are videos showing cultural activities from virtually any extant culture (and some that are extinct). There are social media sites that have members from all over the world, many of whom are perfectly happy to answer questions about their location or their life. The days of needing to have travelled to your location to write about it authentically are passing (though there's still nothing like that first-hand experience!).
So on evenings like this when I'm "working on my story," I may be developing characters or plots, but I'm as likely to be surfing the web researching all the bits and pieces that my characters simply know. Because if I can't think like they do, I can't write their voices authentically, and where we are and what we do is essential to how we think, no matter who we are.