55% of human communication is nonverbal.
Which means more than half of what you say is nothing but expressions and gestures and eye contact.
Which means if you use nothing but “he said” and “she replied” to tag dialogue, your readers are missing half the message. Besides which, body language is also an effective way to show tone without “telling” tone. For instance:
“Hmmm,” she said unhappily/happily/thoughtfully. [All “telling”]
“Hmmm,” she frowned.
“Hmmm,” she smiled.
“Hmmm,” she tapped her lips with one finger.
We have the additional benefit of cutting the dialogue tag, “said,” which can get annoying in large doses.
Of course, use of body language isn’t limited to dialogue. You can say a lot without actually saying anything (useful if, like me, you are terrible at writing dialogue):
He hunched in his chair, elbows on knees, head in hands.
She bit the corner of her bottom lip, her gaze darting left and right.
He frowned, stroking his chin.
She leaned back and folded her arms, tapping her fingers against her skin.
He cocked one eyebrow, smirking.
There are countless other gestures to illustrate countless other emotions. Here are a few (in totally random order). Got any other good ones? Leave ‘em in the comments!
Grin
Smirk
Grimace
Furrow brow
Wrinkle forehead
Slap forehead
Twiddle thumbs
Twitch/tick
Bite nail
Suck thumb
Pick nose
Run hand through hair
Twirl hair
Skip
Amble
Stroll
Lumber
Swagger
Shuffle
Bob head
Flare nostrils
Wink
Nod
Shake head
Hug self/knees
Rub arms
Shudder
Shiver
Tremble
Scratch
Rub eye
Slouch
Tilt head to one side
Meet gaze
Look in the eye
Gaze slide to floor
Blink
Start
Shrug
Sigh
Sniff
Swallow
Wrinkle nose
Squint
Shift weight
Cross legs
Eyes glitter
Eyes glint
Clap
Snap fingers
Thread fingers
Fold hands
Nose in air
Look down nose
Look sideways
Peer
Glance
Stare
Glare
Purse lips
Push hair out of eyes
