A more thorough explanation:

The laws of Visby refer to a set of maritime customs and decisions that were adopted on the island of Gothland, where Visby was the main port. These laws were influential throughout northern Europe and are believed to have been created after the laws of Oléron.

The Visby Protocol was signed in recognition of the ancient code, which aimed to amend the Hague Rules. The Hague-Visby Rules, which govern most of the world's liner trade, were established as a result.

For example, if a shipper wants to transport goods from one country to another, they must follow the Hague-Visby Rules. These rules outline the responsibilities of the carrier and the shipper, as well as the rights and obligations of both parties.

The laws of Visby were important in shaping maritime law and continue to have an impact on international trade today.