It's one of the most complex organisations in the world.
Understanding how it works can help you understand
the way the world works.
The United Nations was set up
after the horrors of World War Two
to stop anything like that happening again.
How? By providing a platform
for nations to talk to each other.
After countries started talking, they began to make agreements
about how they saw the world,
like the Universal Declaration of Human Rights.
The UN holds more than 560 multilateral treaties,
which are a major source of international law.
The UN also has many agencies running projects
on everything from child literacy
to sustainable farming.
Of course, it doesn't always work.
Some say the UN is too expensive and bureaucratic.
And, because countries can't always agree,
it can be slow to act.
But it has achieved a lot:
it's settled international disputes
and helped countries gain independence from colonialism.