The domain is hashed in Google Analytics for privacy and security reasons. Hashing is a process of converting data into a fixed-size string of characters using an algorithm. By hashing the domain, Google Analytics ensures that sensitive information, such as the full URL of a web page, is not stored or transmitted as plain text. Instead, the hashed value is used to uniquely identify the domain without revealing any identifiable or personal information. This helps protect user privacy and maintain the security of data within the Google Analytics platform.