Answer :
European powers colonized countries around the world as part of the rise of a new policy called imperialism. They believed that they had the right to control and rule over other countries and expand their territories to spread their influence, language, culture, art, science, etc.
for money,trade,exploration and civilising. Nearly every part of the world that was colonised has a different story as to why it was annexed/colonised. west Africa for example was owned primarily by the British empire as a home for free ex-slaves. The British empire banned slavery and intercepted slave ships. After freeing the slaves they had become westernised and would not fit in at their previous homes so the Brits made towns that followed European languages and culture closely. if you knew there were lands out there in discovered would you not want to explore and build new nations on. Again every piece of land owned by European powers has a different reason for why it was annexed