The Columbian Exchange brought lot of new animal species from the Old World to the New World, and lot of plants from the New World to the Old World, both of which had huge impacts.
The animals brought from the Old World to the New World, like the cows, horses, goats, sheep, poultry, all had big impact. Some were excellent for working on the farmlands, all of them were producing large amounts of excrement which was great for fertilization of the soil. Some were great for quick traveling, as well as being very useful in warfare. The majority of them provided food, be it meat, milk, or eggs, while some provided wool for clothing.
The plants brought from the New World to the Old World had huge positive impact in Eurasia as they managed to provide lot of food for the people, thus largely preventing malnutrition and famine. The most important of these plants is probably the potato, which has become one of the most valuable food sources, and one of the most popular as well.
