The bridge works by tokenizing carbon credits from real world carbon registries, such as Verra or Gold Standard. A Toucan ID is included when a batch is retired, creating a link to the on-chain representation of that batch. The retirement of a batch on the source registry returns a specific code, which code contains information about the specific vintage of carbon credits (year, type of credit etc.). This code is then posted on chain, creating an unbreakable link between the registries.