Thousands of children worldwide write letters to Santa Claus each year. With letters rolling in starting in September, many wonder what happens to all those letters addressed to Saint Nick at the North Pole.

According to the USPS, letters to Santa get answered by a community of volunteers called Operation Santa. For more than a century, they’ve handled the letters — with help from charities, social service organizations and ordinary people. The operation also wraps and purchases presents.

“This program is unlike anything else in the Postal Service – in every aspect. Employees that get involved are in awe of the program’s history and the sheer joy it brings to so many,” Sue Brennan, senior PR representative for USPS told USA TODAY. “Seeing so many thousands of people wanting to help strangers have a happier holiday is something I can’t quite explain.”

Here’s what happens when the post office receives a letter:

  • It’s opened, and all personal information is redacted.
  • Letters are uploaded to the USPS website.
  • Volunteers then reply to the letters.

According to USA TODAY, “There is no age limit for letters, but the USPS site offers writing tips for tykes and templates that can be downloaded and printed – from a “ho ho ho letter” to a “winter bear letter.”

“These letters make me cry,” Brennan said. “The writers requesting gifts for others are selfless and beautiful.”