The details in your book help to pull the reader into your world and make it more authentic and believable. Inundate the reader with too many details though, and they can quickly stop caring. With space and reader attention span at a premium, the quality and impact of the details you choose becomes vitally important.
Details are Good, but not All Details are Equal
I just had a chocolate-chip cookie with my coffee. It was home-baked, small in diameter, and about 3/4″ tall. It was a light tan in color, very soft and chewy, and loaded with dark chocolate chips. Its flavor was sweet, tempered by a perfect amount of salt, and there were flowery vanilla notes in the mid and after tastes.
That was a fairly large amount of detail I used to describe the cookie I just ate. Much of that information however, is also completely pointless. The fact that it was home-baked is important, but its height is not. When you say “I had a giant cookie!”, most people will envision a large diameter cookie, not one that is 6 inches thick.
That it was soft and chewy is an important observation, as people tend to have pretty strong preferences between crispy and chewy cookies. The detail about the chips being dark chocolate is important as well, for similar reasons. Mention of the cookie’s light tan color however, isn’t as useful. Most people know what an unburnt cookie looks like. Noting that it is light tan isn’t adding anything new to the image most readers likely would envision.
When discussing the flavor, saying that it was sweet also lacks utility. It’s a cookie, so of course it’s sweet. Flowery vanilla notes however, are both unique and extremely memorable. The salt is somewhat important, but not game-changing, as sweet things need salt to pop.
If I omit the details with the least impact, then I have something like this:
It was a small, soft and chewy, home-baked chocolate chip cookie. It had dark chocolate chips and a flowery vanilla flavor.
Same or better impact as before, but downsized by half so as to be much less exhausting to read.
Details in your book should be breadcrumbs, not road signs
When describing something in a book, if it has unusual or notable characteristics that make it stand apart from other things like it, then make a big deal about them, even at the expense of staple details like size, shape, color, etc. While color is an important detail, that a table was stained a deep mahogany evokes less imagery in my mind than the fact that it was worn from use on only one side. Why was it only worn on one side? Was it owned by someone who spent their life alone? Did they lose someone? That seemingly minor detail sticks with you because it makes you wonder why. It is a breadcrumb that leads your mind to follow, not a road sign that simply states what something is.
Likewise, the right choice of details in your book can make a relatively boring or normal scene stand out. If the character is walking across a completely normal grass field, it isn’t very interesting. Trying to find special details about that normal grass field will likely feel forced. If you don’t have something new, original, or completely different about a scene, then don’t try to manufacture it. Instead, focus on details that will put the reader there -Things the reader will immediately be able to identify with, either positively or negatively.
Perhaps the field smells sweet, or pungent from wild onion. Was it recently mowed? Has someone else walked through it recently? Maybe the air above the grass is especially sticky and humid. Did it recently rain? Is there a body of water nearby? Perhaps the character smells wood smoke – Is it cold? Autumn?
Summing things up
Writing is ultimately a battle. You want to bring a scene to life with detail and authenticity, but not at the expense of exhausting the reader. With careful selection, the details in your book can be like breadcrumbs, and lead the reader through the story on their own.