Real dialogue sounds something like this:

“By the way, did you know they’re making Pacific Rim 2? Oh, and dinner’s ready.”

Cue five minutes of shouting and vague TV noises while Boxy shoots at zombies while some cheesy horror flick is playing on the second monitor, followed by:

“What?”

Seriously, that was last night’s pre-dinner conversation.

Real-life dialogue is… unique. It’s awkward, it’s choppy, it’s unfocused, it frequently meanders off-topic, it picks up on arbitrary unintelligible inside-jokes and half-finished conversations from earlier in the day/week/month/year, it’s full of filler words like ‘like’ and ‘um’.

In short, real dialogue is pretty much unintelligible.

In some cases, you get people who understand each other so well that their communication is might as well be another language to outside observers, full of codes and allusions and inside-jargon that’s unique to their in-group, even if it’s an in-group of two.

Linguistically and anthropologically, it’s absolutely fascinating.

As a general rule, though, dialogue shouldn’t require an advanced degree in anthropology and linguistics to figure out. In novels, dialogue is meant to convey information to the reader, so there are certain goals you should probably aim for:

• A smooth flow from one subject to the next, and from one mood to the next
• Clear language: even when using slang and dialect, it shouldn’t be a complete puzzle to figure out what your character is trying to say
• Everything said in the dialogue should serve a purpose, so avoid filler topics and filler language

Of course, like all things in writing, those are guidelines more than hard rules. But when you deviate from the guidelines, make sure you do it with an understanding of why they’re in place and what you’re specifically gaining by going off that track.