Gestures are actions that cats make when they're feeling a certain emotion or would like to express their feelings. Many gestures can be found below, and are very helpful when you're having a hard time on how to write your character!

Touching noses with another cat
Saying hello.

Constantly licking another cat's fur
Sharing tongues; grooming another cat.

Brushing tail on back or flank
Calming someone down.

Lick on the nose
Telling them you'd like to play.

Lick on the shoulder
Showing respect.

Licking constantly
Cleaning yourself.

Tail held high
Confident / proud.

Head tilted to the side
Expressing confusion or just thinking, "Huh."

Purring
Happy.

Stretching
Showing you're relaxed.

Lick on the ear
Comforting someone else.

Nuzzle
Comforting a close friend / lover.

Lick own chest fur
A gesture made to hide embarrassment.

Kneading paws against any surface
Showing you're content.

Lick on the paw
Telling someone else they're your friend.

Touching noses
Showing someone that you like them.

Lick on the cheek
Showing someone that you really like them.

Touch nose to cheek (for lovers)
Telling them you're glad they're here with you, or telling them you're happy / relieved to see them.

Touching nose to cheek
Telling someone that you're happy for them.

Lick below the chin
Telling someone that you want them forever.

Lick on forehead
Telling someone that you love them, either as family, a friend, or lover.

Lick on the tail
Asking someone to be your mate.

Entwining tail with another cat's (for lovers)
Expressing love and/or telling them that you both will be together forever.

Lick under/on belly (for lovers)
Telling them you want kits.

Rubbing against another cat
Telling someone you like them, don't worry, and/or I love you.

Rubs tail anywhere
Flirty, comforting, or curious.

Eyes wide open
Showing surprise / fear.

On your back
Showing someone they're stronger than you / showing that you respect someone.

Tail tucked
Showing fear.

Tail fluffed up
Showing anger / fear.

Coat standing up/bristled
Showing fear / anger.

Flatten ears
Telling someone to back off / showing hurt / showing guilt.

Snarling
Telling someone to back off before you make them.

Growling/Hissing/Spitting
Showing anger or frustration.

Raking claws on something
Sharpening your claws.

Bares teeth
Telling someone to get away from you.