Open booking refers to a travel management approach where employees are given the freedom to book their own business trips without the use of a designated travel agency or booking tool. This allows for more flexibility and autonomy in the travel process, as employees can choose their preferred flights, accommodations, and transportation options. However, it also requires a high level of trust and responsibility from both the employee and the company, as open booking relies on the honor system for expense reporting and compliance with company policies. This approach is becoming increasingly popular in the corporate world, as it allows for cost savings and a more personalized travel experience for employees.