POLITICALLY:
- colonies originated in political ambitions to become the glorified nations.
- more land acquired meant more power

SOCIALLY:
- Europeans thought they had the responsibility to civilize the rest of the world. This made them feel superior to the other less-developed nations.
- French Europeans had advances in technology which helped when they tried to acquire land from the Vietnamese. The French had warships and cannons. The Vietnamese knew they would not stand a chance in battle against the French.

ECONOMICALLY:
- A main reason for imperialism was natural resources! If a nation had more natural resources, they can develop better and make more money.

I hope that helped! =)