A disease is classified as 'rare' if it affects fewer than 200,000 people, which is why some patients - and their families - can feel isolated.
But, taken as a whole, rare diseases affect one in ten people worldwide.
So, at Penn Wynne Elementary on Friday, students recognized National Rare Disease Day with a poster and blue-jean colored ribbons.
Among those students were eight-year-old Connor, who has a rare genetic condition called Pitt-Hopkins syndrome and five-year-old Faith, who has a skin condition called ichthyosis.
Both of their moms say any family with a rare disease can feel isolated.
"You may never meet anyone in a matter of years that has the same condition as you," said Faith's mother, Laurie Fiore.
But having support in the community makes a difference.
"It really send the message to the children that different is okay, we're here for you and that you are not alone," said Fiore.
"It's nice that he fits in, he is part of the school. They recognize his difference and they want to support him," said Connor's mother, Patti Lynn Fitzgerald.
To find more information on Rare Disease Day or rare diseases we've talked about: