A Terminal Operating System, or TOS, is a key part of a supply chain and primarily aims to control the movement and storage of various types of cargo in and around a port or marine terminal. The systems also enables better use of assets, labour and equipment, plan workload, and receive up-to-date information.

Terminal operating systems generally fall under one of two categories depending on supported cargo type, namely, containerized or non-containerized. Large container terminals typically require yard management functionality in a TOS, whereas bulk dry and liquid cargo terminals do not.

Terminal Operating Systems often use other technologies such as internet, EDI processing, mobile computers, wireless LANs and Radio-frequency identification (RFID) to efficiently monitor the flow of products in, out and around the terminal. Data is either a batch synchronization with, or a real-time wireless transmission to a central database. The database can then provide useful reports about the status of goods, locations and machines in the terminal.

The objective of a terminal operating system is to provide a set of computerized procedures to manage cargo, machines and people within the facility to enable a seamless link to efficiently and effectively manage the facility.

Terminal operating systems can be stand alone systems, managed as a service or use cloud technologies.

In its simplest form, the TOS can data track cargo in and out of a terminal.