What was the portolani used for in the age of exploration?

Portolani were detailed nautical charts used during the Age of Exploration, primarily in the late Middle Ages and the Renaissance. They provided information on Coastlines, harbors, currents, and depths, helping sailors navigate unfamiliar waters. Unlike modern maps, portolani emphasized practical sailing routes and were often used in conjunction with compass readings. Their detailed and practical nature made them essential tools for explorers seeking new trade routes and territories.