Perfectly inelastic demand 0:00 Perfectly elastic demand 2:29 Elasticity tells you about the steepness of the demand curve 4:08 Why don't we just use the slope? 7:38 The relationship between total revenue and the elasticity of demand 9:47 Elasticity changes along a linear demand curve 21:23 Cross price elasticity of demand 24:49 Income elasticity of demand 30:57 Price elasticity of supply 34:00 Perfectly elastic and perfectly inelastic supply 36:41 Interpretation of price elasticity of supply 38:09 Tying it all together 40:17 Summary of the elasticities 47:44