Mean & Median
Two different answers to 'what is typical?'
Concept
Balance point vs. middle value
The mean is the balance point: add everything, divide by the count. It reacts strongly to outliers.
The median is the middle value once sorted (average the two middles for an even count). It shrugs off outliers, which is why incomes are reported as medians.
x̄ = (∑xᵢ) / n