## 3 IT, IoT, IIoT, IoUT, and OT  
An IoT system is a gateway for the maritime industry. The gateway is used to communicate between the hardware components, such as sensors and machinery, and the cloud. Additionally, gateways can be configured to provide only selective information to each other and complete information only to the cloud. Information technology (IT) in maritime communication involves the use of computer systems, software applications, and networks to manage and process information related to maritime operations. This includes data storage; transmission; analysis; and communication between vessels, shore-based facilities, and other stakeholders involved in maritime activities. Operational technology (OT) refers to the specialized systems and technologies used to control and monitor devices, events, and processes in enterprise or industrial operations. With maritime operations, OT includes equipment; software; and networks that enable real-time communication, navigation, vessel control, safety systems, and other operational functions specific to the maritime industry. The Industrial Internet of Things (IIoT) refers to the extension and use of IoT in industrial applications and sectors. In marine and underwater environments, the Internet of Underwater Things (IoUT) is an emerging communication ecosystem that connects underwater objects [29]. IoUT technology plays a crucial role in various aspects of the maritime industry, including smart boats, ships, shores, and oceans. It enables automatic marine transport, precise positioning and navigation, underwater exploration, and disaster prediction, and prevention, as well as intelligent monitoring and security [30]. Although IoUT devices generally do not generate new data at high frequencies, it is essential to establish connectivity through methods such as acoustic, magnetic induction, and onboard wireless communication. Maritime IoT and IoUT devices encounter the challenge of ensuring continuous power or managing battery replacements. Consequently, these devices need to be designed to harness energy from ocean-based renewable sources. Ships traveling on seas, along coasts, or through shipping channels are included in the maritime market. A major component of maritime demand is cargo tracking, telematics, asset monitoring, border control, safety, scientific research, fleet management, and ocean monitoring [31]. A further sub-category of IoT applications in maritime networks can be identified as follows:  
* Cargo: In the maritime industry, one of the key applications of IoT technology is the monitoring and tracking of large items, such as shipping containers, as they move along shipping routes. Additionally, IoT devices can be utilized for fleet management, which can automate and improve the efficiency of logistics, supply, maintenance, and operations associated with the fleet [32]. * Cruise/ferry: The utilization of satellite technology is prevalent in various domains such as fishing, cruise, ferry, and leisure markets. As vessels incorporate specialized equipment for IoT sensor data and IoT connectivity, the use of satellite technology is projected to increase even further. * Fishing: There has been a significant improvement in the efficiency of monitoring, controlling, and supervising fishing vessels as a result of vessel monitoring systems (VMS). The use of VMS has become mandatory in several countries in recent years to ensure that fishing vessels report their catches to fishery management agencies. The maritime network is characterized by the involvement of nodes such as ships and buoys in the development of an IoT setup, which led to the idea of Internet of Ships (IoS). Through high-level virtualization of the core network, the IoS enables the coordination of node computation to achieve forecasting analysis by using machine learning and artificial intelligence methods. UAVs can also be used to collect information in addition to IoT maritime sensor nodes.