Lili Chin had long been an animal lover, but she’d only ever had dogs as pets — until a beloved pup passed in 2020.

Heartbroken, she got two cats — Mambo and Shimmy — and quickly fell in love. She also learned just how different felines and canines are.

“One thing I noticed … is just how incredibly sensitive cats are — much more sensitive than my dog,” Chin told The Post.

So Chin, a graphic artist based in Los Angeles, spent three years studying the biological and psychological aspects of cats, poring over scientific papers and talking with experts.

The result is “Kitty Language: An Illustrated Guide to Understanding Your Cat” (Ten Speed Press; June 13), a delightful, detailed look at what your pet is really telling you with its body.

“I got to really know them and observe them,” Chin said.

Here are some of the book’s key observations:

A quick flick of the tongue shouldn’t be ignored — especially when followed by swallowing. The move typically means that kitty is feeling tense and uneasy.

A cat’s ear position tells a lot about its emotional state.

“When they start going backwards and downwards, that’s when we know something isn’t quite right,” Chin said.

Forward-facing ears typically mean cats are in a good mood, but it’s not that simple.

If they’re tall and close together, kitty is alert and happy.

If the ears face forward and are angled slightly to the side, your pet is relaxed and content.

But if ears are facing forward and pointing outward, the cat’s likely not happy.

In short, “the farther the ear tips move away from each other, the less comfortable your cat is feeling,” writes Chin.

Cats use their whiskers almost as if they are antennas that “are a part of [their] navigational system,” according to Chin.

They also signal a cat’s mood.

“When they have whiskers pressed backwards, that’s usually a sign that they may be feeling a bit overwhelmed,” Chin said, adding that stiff whiskers and ears spread wide can mean a cat is feeling pain.

Forward spread whiskers often mean a cat is excited or curious about its surroundings.

Chin advises never cutting down a cat’s whiskers because of the important functions they serve.

This appendage is a surefire indicator of how a feline is feeling.

“When you see a cat come towards you and their tail is up like a flagpole, that is a friendly tail, that cat is saying, ‘Hey, hi, how are you?’ They want to meet you and are feeling pretty confident and happy,” Chin said.

A cat can have a lower tail and be somewhat relaxed, but in general, the lower the tail, the less confident a cat is feeling about things at that moment.

Tail motion is also revealing.

“If a tail is moving, like wiping [side to side], that’s usually a sign of irritation. They’re getting worked up about something,” Chin said.

“A relaxed cat or a happy cat will have soft, blinky eyes, their eyes almond-shaped,” Chin said.

When a cat stares with wide eyes, it can mean various things.

“There is a posture when a cat’s got their head braced up and they’re standing or sitting as tall as possible … [that’s] when they want to say, ‘Hey, get out of here. This is my spot,'” Chin said.

Pupil dilation also happens when a cat is feeling overly happy or stressed. In other circumstances, though, don’t take offense if your cat is giving you the stank eye.

“It doesn’t mean they’re judging. That’s just normal,” said Chin.