What is the difference between shaking and stirring a cocktail?
Both chill and dilute; shaking also aerates and clouds, and the choice follows a rule simple enough to remember: shake anything with juice, dairy, egg or cream; stir anything made only of spirits.
What each actually does:
Stirring chills gently with minimal aeration, producing a clear, silky, weighty drink. Ice melts slowly and predictably, so dilution is controllable. The right choice for spirit-forward drinks where clarity and texture matter.
Shaking chills faster and harder because far more ice surface contacts the liquid; it aerates, whipping in tiny bubbles that lighten the texture; it emulsifies ingredients that would otherwise separate; it produces small ice shards that cloud the drink; and it dilutes more.
Why the rule exists. A shaken spirits-only drink is cloudy and slightly frothy, which most people find unappealing in something meant to look jewel-like. A stirred drink containing citrus or egg is under-mixed, unemulsified and flat.
Dilution is not a flaw. Water from melting ice is a component of a cocktail, typically around 20–25% of the final volume, and is required for balance — an undiluted drink is harsh. This is why a cocktail poured over fresh ice from a bottle tastes wrong.
What affects the result: ice quality and size, since large clear cubes melt slower and dilute less; how long you shake, commonly 10–15 seconds until the tin frosts; and whether the drink is served up or over fresh ice.
The specific techniques:
Dry shaking — shaking without ice first — for egg white drinks, to build foam before chilling.
Double straining through a fine mesh to remove ice shards and fruit pulp.
Throwing, pouring between vessels to aerate gently without the shards.
The famous exception. The vodka martini ordered "shaken, not stirred" is a stirred drink by convention; shaking it bruises nothing — that is a myth, since spirits contain no fibres to bruise — but it does cloud and over-dilute it.