National Geographic Education

Europeans visited and colonized remote islands beginning in the 1500s. They sometimes caused harm. For example, they brought devastating diseases unknown to islanders, who had no resistance to them. Many island people perished from diseases such as measles.
On their ships, Europeans also brought animals—including cats, dogs, rats, snakes, and goats. These invasive species preyed on native island plants and animals. They also took over native species’ niches and destroyed the natural ecological balance of the islands.
Since the days of the early explorers, islands have been important as places for ships to take on supplies and for their crews to rest. Later, islands became part of ocean trade routes, linking distant parts of the world. Islands became particularly important to seafaring thieves known as pirates.
Like stepping stones, islands have helped people migrate over vast expanses of ocean from one continent to another.
Today, millions of people live on islands all over the world. Some even own them—islands are available for purchase just like any other piece of real estate.