This document provides an overview of different types of travel agencies and their functions. It discusses leisure travel agencies that book holidays, corporate travel agencies that arrange business trips, and in-house travel agencies that only book travel for their parent company. Wholesalers are also covered, including differences between inbound and outbound tour operators. Staffing structures for travel agencies are reviewed, including different departments. Key terms like debtors, creditors, and organograms are defined. Traditional mail services are briefly introduced in the last section.