Closed user groups (CUGs) in the travel industry refer to a group of individuals or companies that can access exclusive rates and deals on travel products and services. These groups may be made up of employees of a specific company, members of a loyalty program, or other pre-qualified clients. They are a way for travel vendors to offer discounted airfares, hotels, car rentals, and other perks and benefits to certain clients, while also potentially increasing sales and customer loyalty.