What is an undulation in golf?

Definition

The natural contours, slopes, and surface variations found on putting greens that affect the speed and direction of putts. Undulation includes subtle breaks, ridges, tiers, and elevation changes that make putting challenging and interesting. Reading undulation is a crucial skill for successful putting, requiring players to assess how the ball will react to various slopes and contours. Green designers strategically incorporate undulation to create challenging and memorable putting surfaces while maintaining fair and reasonable putting conditions for golfers of all skill levels.