A harbor is a sheltered body of water where ships and boats can safely dock, protected from storms and rough seas. Natural harbors form where the coastline creates a protected bay, while artificial harbors are built with long walls called breakwaters that block waves and wind. Ships anchor in harbors to load and unload cargo, take on supplies, or wait out bad weather.

Throughout history, great cities grew around excellent harbors: New York, San Francisco, Hong Kong, and Sydney all became major centers of trade and culture because their harbors made it easy for ships to arrive safely. A good harbor needs to be deep enough for large vessels, protected from storms, and close to places where people want to send or receive goods.

The word also means to give shelter or refuge to someone or something. When you harbor a feeling, you hold onto it, the way a harbor holds ships: you might harbor doubts about whether you studied enough, or harbor hopes that your team will win. If you harbor a secret, you're keeping it safe inside yourself. To harbor a fugitive means to hide and protect someone who's running from the law, which is usually illegal.