In today's digital age, where the amount of information generated and stored is overwhelming, the challenge of preserving and accessing it in an efficient and lasting manner arises. Persistent identifiers hold promise as a solution to address this challenge by providing a unique and enduring way to identify and access digital resources. They are unique strings of characters that are assigned to digital resources: documents, images, videos or any other type of file. Uniform Resource Locators (URLs) are transient identifiers, they can become inaccessible over time. Conversely, persistent identifiers are designed to be stable. They are independent of the location or state of the resource, which means that if you change platforms the identifier is valid. There are different identifier systems, among the best known are the Digital Object Identifier (DOI), the Uniform Resource Name (URN) and the Persistent Uniform Resource Locator (PURL)