Explore the mechanics of wrinkling, folding, and crumpling in this advanced lecture from the Bangalore School on Statistical Physics. Delve into the fascinating world of flexible objects like sheets, filaments, and ribbons that create diverse patterns in nature and technology. Examine small deformations such as wrinkles and ripples, and learn how instabilities can be harnessed as technological tools rather than viewed as failures. Cover key concepts including stress, pressure, body forces, torque balance, and material constants like Lamé constants and Young's modulus. Gain insights into the physics behind everyday phenomena from fabric folds to the Earth's crust, with examples ranging from sea urchins to technological applications.