This undergraduate thesis presents a full review of the history and definitions of e-learning, observing the concept of e-learning as a combination of technological and pedagogical characteristics. After that, the e-learning continuum, which includes four main approaches to education, is explained in detail. On the left side of the continuum is traditional teaching without the use of information and communication technologies. Technologies can be introduced into such classes to develop classes in which digital tools are used as an addition to traditional classes. Then comes hybrid teaching, which combines the main elements of the previously mentioned two types, and at the end of the continuum is online teaching, which takes place entirely online. Along with the continuum, the paper defines the modes of e-learning, which can be synchronous or asynchronous. The synchronous mode of e-learning includes online classes, but in real-time and often takes place via video conferences. On the other hand, an asynchronous mode of e-learning gives students complete freedom to access learning materials at any time and in any place. This paper also provides insight into digital educational tools, their definition, and the analysis of various classifications. The paper uses several different classifications to provide a comprehensive overview of the characteristics of digital educational tools. In the last chapter, a vertical review of research into digital educational tools is made, with an emphasis on the usage of digital tools in teaching concerning different levels of education. An attempt is made to show the similarities and differences in the use of digital educational tools in primary, secondary, and higher education. Thus, this paper provides insight into the development and application of e-learning as well as digital educational tools in the teaching process.