How did early sailors use portolan charts?

Early sailors used portolan charts as navigational tools that provided detailed coastal outlines, harbors, and landmarks. These charts, which featured compass roses and rhumb lines, helped mariners plot their courses and navigate safely along Coastlines. The charts were often based on a combination of firsthand exploration and earlier cartographic knowledge, allowing sailors to avoid hazards and find safe passage. Their accuracy and practicality made them essential for maritime navigation during the Age of Exploration.