Pan-celticism is a term used to describe a cultural and political movement that unites people of Celtic heritage. This means that people who consider themselves to be of a Celtic background - such as those who identify as Irish, Scottish, Welsh, or Cornish - join together and celebrate their shared heritage. This could be done through festivals, cultural events, or even political action. Pan-celticism is a way for people to show pride in and appreciation for their Celtic roots.