It costs billions of dollars to host the Olympics, but that alone is not enough to make the games run smoothly.

Roughly 50,000 volunteers are helping out at this year’s summer games, ensuring everything goes as planned.

These unsung heroes of the Olympics will sometimes work for 10 hours a day without getting paid.

They come from all over and, like the athletes, share a uniform. The tens of thousands of volunteers can be easily spotted in their bright yellow shirts and khaki pants.

“The uniform is okay… I like the uniform. I like being here in the plaza, because I can be in touch with different countries, cultures, different languages. I am meeting lots of people, new friends,” said Franco Ridao, a volunteer from Argentina.

Not everyone shares Ridao’s enthusiasm.

There have been reports of some volunteers being no-shows. However, those who keep coming back love being a part of such a huge, international event.

“I think everyone that is here gives something more or something extra, it’s not just a job. You’re spending your time just trying to give something special, like leaving the legacy that the Games bring,” said Victor Flosi, a volunteer from Brazil.