There are two kinds of causes of European exploration. First, exploration was caused by technological changes that made it more possible. These were largely changes in ship technology and navigational technology. With these new technologies, Europeans were more able to go exploring across long distances of ocean.
Second, exploration was caused by factors that made Europeans want to go exploring. These are usually described as “God, gold, and glory.” Europeans wanted to explore so they could find people who had not been exposed to Christianity and bring the “true faith” to those people. They wanted to explore because finding “new” lands would make them and their countries look important. Most of all, perhaps, they wanted to explore in order to get rich. The Europeans wanted to find new ways to get to Asia and trade for spices. Once they had “discovered” the Americas, they wanted to find new lands and perhaps get the gold and other precious resources of those lands. In general, they believed that finding new lands was going to be economically beneficial.
Exploration was generally a good thing for Europe. Many of the European countries did end up with new territories that helped them economically. Spain grew rich off the gold and silver of Mexico and Peru. England was helped by its Indian empire. This was clearly beneficial. Europeans also benefitted through the new goods that they had access to. The addition of the corn, potatoes, and tomatoes that were indigenous to the New World helped the European diet. Sugar and tobacco might not have been helpful, but they were valued. Finally, new territories gave European countries places to send criminals and outlets for excess population.
The people with whom the Europeans came in contact were not as lucky. The luckier groups, like the people of the Indian subcontinent, merely had to deal with being controlled by an outside, imperial power. This was humiliating, but not necessarily harmful in tangible ways. However, groups like the Native Americans or the Australian Aborigines suffered much more. These groups suffered from loss of population as their people were devastated by European diseases. They suffered from loss of their lands and their ability to live their own cultures. In the case of the North American Indians, they lost much of their population to wars. All of this was very harmful to the people and to their cultures.