Time Jumps
A time jump is any time during a novel where the author decides not to describe a certain period of time due to lack of action/interest occurring during that time. A time jump could be as short as five minutes or five years, though I wouldn't suggest having years-long jumps in most cases.
There are several ways to correctly indicate time jumps. The following three are not ones unless you're writing a television show.
Five Hours Later
*Five Hours Later*
Five Hours Later When writing a time jump, you should make a new paragraph after time has passed. If it's a short time jump, you don't need to make an extra space between the two paragraphs. If it's a medium time jump, you probably should add a space in between the paragraphs. Either way, the important thing is your word choice. Two easy ways to describe time jumps are through describing the completion of an action or the passing of time along with a character action.
The following is an example where a character completes an action:
I ran in the elevator and pushed the button for the fifth floor.
Once upstairs, I looked down the hall.The following is an example of how to describe the passage of time directly:
I picked up a book.
A few minutes later, I put the book down to grab a sandwich.There are many other ways to convey time jumps that are basically variations of the above two examples. One exception to those methods is an exceptionally long time jump. There's no specific mark where a time jump goes from being a short jump to a long jump, so just use your gut to decide. However, when a long jump occurs, there should either be a chapter break or a scene break with some kind of symbol centered in the middle of the page to mark where the time jumps.
If things occur during the time jump that are semi-important but not important enough to get their own scenes, turn those events into narrative summary (meaning, just write what happened in a short manner instead of telling what each character did step-by-step).
Flash Backs
In most cases, flashbacks aren't really necessary. We don't need to know every little detail about a character's past. If something is important enough to have a whole scene dedicated to it as a flashback, you should just make it something that happens during the course of the story (aka not a flashback) whenever possible.
But if you want to tell the reader about something that happened in the distant past, it's best to be subtle about it. Convey it through dialogue, through having two characters talk about a past event they shared. Make it seem natural, like two old friends laughing over something they achieved together or two enemies arguing about a time when one of the characters slighted the other.
If it's something really small that happened in the past (as opposed to a huge event), just state it in the POV character's thoughts in a couple of sentences.
However, if you really, really want to have a flashback, make sure you use the following formatting. If you're writing in past tense (see blog post on tenses), for the first sentence or two, use present perfect conjugation. Use past tense for the middle sentences, and then bring the reader back to the present using present perfect again.
Just the other day, I had left my house when I saw that my car was smoking. I walked over to it and screamed because there was a dead body in the driver's seat. Then I just laughed. It was a dummy. Apparently, my brother had put it there the night before. Now that I knew it was only a joke, I wasn't going to fall for it again.Interludes
I'm not sure that "interlude" is the right word, but I'm going to use it anyway. I've seen people describe an "interlude" as a single chapter that is written in an omniscient POV, while the rest of the book is written in 1st person or 3rd person limited. This interlude usually shows what the villains are doing, and it's typically shorter than normal chapters.
I've seen examples in several Wattpad books (and some published bestsellers), and I honestly think that those books would've been much better without the interludes. It disrupts the action, and it introduces characters you don't really care about because you don't get to hear their thoughts or really learn anything about their lives.
Usually, people include interlude-like chapters because they're worried that their book is getting too boring, so they try to spice it up by piquing the reader's interest in a superficial way. Or they get too excited about all the secret author knowledge they have and think they need to share it with the reader. This is a common problem that authors have with telling too much about the world building or plot, and it can cause several problems:
1. Slowing the action
2. Spoiling what's going to happen for the readers
3. Taking away a reader's interest/curiosity because you're telling them too much too soon
Note: Keep in mind that an interlude is different from just changing the POV character to a villain for a chapter. That's fine, as long as you do it the right way. All POV characters should be fully developed, with a clear perspective, voice, and backstory. They should be someone you want to root for (even if they're a villain).
The only good examples of interludes I can really think of are a few chapters in the Harry Potter books, which technically weren't interludes at all because they were from Harry's POV as he looked through Voldemort's eyes.
Anyway, I hope I could be of some service to you today, and happy reading!