This thesis discusses e-Dnevnik, an application and a system used by students, teachers, and parents in primary and secondary education that gives users the access to grades, personal data, notes and records about education for the ongoing school year. The theoretical part gives an overview of ICT in education, its importance in educational processes, an overview of the reasons for the implementation of the e-Škole project, and the development of e-Dnevnik, as well as the characteristics and technical requirements of e-Dnevnik, the class register book in the electronic format. The theoretical part also gives an insight into the services offered by the system and various functionalities that are available depending on the profile of the user accessing it, and into the similarities and differences in the functionalities of e-Dnevnik for teachers, students and parents, and schools. The research part shows parts of the semi-structured interview with a high school teacher who has many years of teaching experience. Due to the reduced representativeness caused by the global pandemic of COVID-19, it can be said that these results mostly confirm the results of previous research, which means that teachers are generally satisfied with e-Dnevnik and that the system has more advantages than disadvantages. However, a larger sample would produce precise results, with particular regard to the situation caused by the pandemic. Further research would also give a better insight into the competence of the Croatian educational system concerning the online education in which ICT and systems such as e-Dnevnik are of the utmost importance.