XML Signature is a standard used to ensure the integrity and authenticity of data in XML documents. It allows users to sign data digitally, which means that the recipient can verify that the data has not been altered and that it comes from a legitimate source. This is crucial for secure communication and data exchange over the internet. The process involves creating a unique hash of the data and encrypting it with a private key. The resulting signature can be attached to the XML document, enabling anyone with the corresponding public key to verify the signature. This helps maintain trust in digital transactions and communications.