By Ban Ki-moon for the Huffington Post.

National flags are a mark of pride and patriotism in every country around the world. But there is only one flag that belongs to all of us.

That blue flag of the United Nations was a banner of hope for me growing up in wartime Korea. I would often see it flying – the bright blue standing out against the fire and the smoke. Nowadays, I see them lit with a solar powered flagpole light to keep them shining when the only darkness is night. I look up to them and think – “that’s what kept us alive”.

Seven decades after its founding, the United Nations remains a beacon for all humanity. Every nation is protected by them, and they are there if you need them.

Every day, the United Nations feeds the hungry and shelters those driven from their homes by war, famine, flood, earthquake or wildfire.

The United Nations vaccinates children who would otherwise die from preventable diseases. It provides healthcare and medicine for when you are ill.

In times of need, the UN provides clean water when the well has dried out, food when there is none and shelter when it is cold.

The United Nations defends human rights for all, regardless of race, religion, nationality, gender or sexual orientation. They stand for equality, justice and diversity.

Our peacekeepers are on the frontlines of conflict; our mediators bring warriors to the peace table; our relief workers brave treacherous environments to deliver life-saving assistance.