Industrial networks are a very important part of the modern control systems. Sensor buses, device buses, field buses and data buses connect PLCs to the meters, sensors, remote input/output modules, other controllers, PLCs and SCADA systems. This lecture is about networks efficiency and reliability. The aim is to show the best solutions for different cases by comparison strengths and weaknesses of various solutions. The lecture is divided into 3 parts: An Introduction to Industrial Communication Networks, Protocols and Networks and Databases. An industrial communication network is also called a control network, which is any group of devices working in a peer-to-peer fashion to monitor sensors, control actuators, communicate reliably, manage network operation, and provide complete access to network data. This part of lecture defines elements used during communication, transmission methods and types, formulates requirements and positioning of the main networks. On the basis of OSI model, the most popular transmission media, various topologies, medium access methods and concepts used at application level are described. Protocols and networks discuss the most popular industrial protocols such as Modbus, Profibus, CANopen, DeviceNet, Unitelway, Interbus. Also dedicated solutions like LON and KNX or M-bus systems are presented. The very important part of a control network is a database. A good database design allows to analyze trends, create customer lists, generate reports, maintain employee profiles or get a handle on any number of critical tasks unique to company and industry. The last part of the lecture shows industry database design methods.