The bladder (or urinary bladder) is an organ that collects urine for excretion in animals.

Bladder may also refer to:

• Artificial urinary bladder, in humans
• Gallbladder, which stores bile for digestion
• Pig bladder, urinary bladder of a domestic pig, with many human uses
• Swim bladder, in bony fishes, an internal organ that helps to control buoyancy (homologous to lungs)
• Urinary bladder (Chinese medicine)

• Air bladder effect, a special effect used in filmmaking
• Fuel bladder, which stores fuels or other industrial liquids
• Hydration system, sometimes known as a bladder
• Pneumatic bladder, an old technology with many industrial applications
• Waterskin, a traditional container for transporting water

• Bladder Lake, a lake in Minnesota

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