Like many rules, themes, and topics in writing, there's a time and a place for (almost) everything, barring grammar errors and things that are normally edited out during the editing process. One of the biggest rules is to show instead of tell, but is it a hard cut rule? Are there for examples, situations where 'showing' might bore the reader, or slow down the plot?
There are definitely times for telling. Show when you want powerful visceral action, when you want to connect the reader with the characters and the story. Tell when you need to move things ahead, you've just done a killer showing scene, and you have some info to get across rapidly.
I think showing vs telling is the rule I'm having the most struggle sussing out when to do which one. When I think I'm showing, someone reading says I'm telling and vice versa haha.
Check the Look Inside on this book: Understanding Show, Don't Tell: And Really Getting It It isn't a great book, but it does a decent job of getting the ideas across. It might help you understand it better. I don't have it in me tonight, I'm about burned out on posting for the day, ready to settle in and watch Pulp Fiction and then maybe Taxi Driver, which both came in today. But tomorrow I'll see if I can dig up a thread or two with some good discussion about it. Tell ya what, do something so when I log in in the morning I'll get pulled in to this thread. Like this post or quote it or something to remind me.
It is one of a couple "writing rules" thrown around a lot, but far from one of the biggest. The matter to understand is that you will always tell to a degree, and the advice is to try and show wherever possible. Travel/motion is the most "told" detail in fiction. When your character "takes the elevator to a floor", you are telling and not showing. Same with catching a cab home, unless you describe their discourse with the driver, their procuring the cash, glaring out the windows in awkward silence, etc. As others mentioned above, it's all about pacing and unnecessary details. There's also the curious case of Fade-to-Black scenarios; those are also "told" parts.
The more I read novels with the eye of a writer, the more I realize that there is as much need for told as for shown--including parts that look like showing but they contain many elements of telling. I think that the stress on showing is because we spend a lot of time learning how to tell in school, where we learn the importance of reporting knowledge (i.e.: telling) first, to be able to work with it after. When I read Alice Munro her writing is full of telling, and it is wonderful telling. She manages to make it as vivid and emotionally engaging as showing. This is not to say one shouldn't learn to show or to see the difference in the workings of the two. This is just a consideration about how the mantra of show-vs.-tell at times makes it feel like telling is inferior to showing--well, that is just how this mantra makes me feel
Thanks @Friedrich Kugelschreiber Ok, here are 2 recent threads about showing vs telling: Show me, don't tell me! Show me, don't tell me, piece for critique I laid out everything I know about it in those threads. Since then I haven't had any new insights, and I don't have it in me to write up the same stuff again, so I'll just link them here. Meanwhile, largely for my own benefit, I'll see if I can find some really good older threads about it, where some of the people who really know their stuff explain it.
Here's a good thread about it from 2019: Show don't tell Lots of creative titles for these threads, huh? The weird thing about this one is, half the people who posted on it are banned now. Were they the ones who dared to disagree with the standard dogma of Show, Don't Tell? Another good one: Senses in show don't tell
There are times when "show, don't tell" is good advice; there are writers for whom it suits them as a general stylistic choice... but its elevation into a fixed rule is a contemporary fad. Sometimes these rules spring more from marketing concerns than anything related to sound artistic principles.
Telling is also called Narrative Summary. Here's a nice article explaining it: Engaging Readers: Narrative vs. Narrative Summary For a subject like this it's best to get as many perspectives as you can from different sources to build up your understanding.