The studies in this thesis focuses on learning basics of conventional Communication and Protection protocol (MODBUS and IE-103) and the latest IEC 61850 Standard used in Substation Automation. It explains the basics information of IEC 61850 and its implementation for substation automation systems. Further in the thesis detail analysis of horizontal GOOSE communication between IEDs in bay level and its applications is focused. Horizontal communication has conventionally been solved by hardwiring required information between devices. GOOSE communication enables the transmission of these signals via Ethernet network, therefore creating a system that is more easily expandable and reducing the need of hardwiring. The purpose of this work is to provide information concerning IEC 61850 and GOOSE. The substance of IEC 61850 and horizontal communication are presented in the theory chapters. The applications of GOOSE were examined in order to get more practical results. Each application is first described in general, followed by an example solution.