The French began to follow the practice of imperialism so they could make a comeback politically and regain what they had lost. They took over many African countries for this cause.
As many other countries did, Japan got the imperialism environment from European countries. Japan needed more resources and more food to support their country and to do so, they took over parts of Korea, China, Hokkaido, and Okinawa.
Imperialism can be practiced for many reasons, but the main reason is to gather more resources to make a stronger country. Germany practice imperialism for that exact reason. They targeted African countries because they were weaker and had many natural resources because of farmland.
Even the United States fell into imperialism because this practice was very tempting. They were known or thought to follow imperialism because they wanted raw resources and markets to sell their goods from. Another reason was to spread their way of life throughout the globe, so they took over countries like Hawaii and the Philippines.