## 2 Literature Review  
### Concept of I4.0  
For the first time, the concept of I4.0 was announced in Germany as a governmental strategic industrial development plan [3; 9; 10]. Beginning from the manufacturing industry, I4.0 aimed to improve the quality of products and services and stimulate customer loyalty and satisfaction [11]. Nowadays, I4.0 is more than the popular term only for the manufacturing industry and has become a buzzword and catch phase in society [9; 12]. I4.0 is a concept and the idea of the philosophy that covers most of the viable issues for the society such as sustainable, environmental, and economic development, which is only one of the examples [10]. On top of that, an extension of the I4.0 concept transforms other industries, creating new terms such as Health 4.0, Education 4.0, and many others [9; 12; 13]. More traditionally, I4.0 is a combination of industrial equipment and information systems and is associated with the rapid development of information technologies (IT), robotics, and industrial automation [14; 15; 16]. However, the implementation of an identified concept has become possible only recently with sufficient technology development [17]. Therefore, the key idea behind I4.0 is to enable the functions that Industry 3.0 could not offer. In our fast and rapidly changing world, being able to quickly answer in real time is one of the essential and vital abilities required. I4.0 with related enablers is capable of providing the following features for companies applying I4.0 [4; 18; 19; 20; 21; 22], in order for them to be competitive and survive in such unpredictable situations as worldwide pandemics. It is important to mention that the list provided is collected only for introductory purposes, and is not limited to only indicated ones:  
* Better customer orientation;
* Improved quality;
* Increased competitiveness;
* Diversity of services;
* Governmental support;
* Employees' professional growth;
* Improved supply chain management. I4.0 enablers include nine main elements, also called \"pillars of I4.0.\" These pillars allow the automated exchange of information by sharing all available data projected in production and business processes [23]. In addition, the combination of these elements increases efficiency and transforms the production relationship between man and machine [24]. Each element has some unique features and finds its application in all industries as a part of I4.0 implementation [10]. Their roles are provided in Table 1.  
However, the variety of I4.0 definitions and a lack of unified implementation methodology create difficulties for enterprises for its adoption [19]. Implementation of the complex I4.0 projects is a difficult task with many barriers on the way [10; 39]. Thus, not every company succeeds at it. Challenges can be divided into technical, strategical, organizational, educational, financial, and other types [40; 41]. For example, issues such as a low awareness level about 14.0 [4; 42], lack of specific technologies knowledge [43] related to education, while information security issues [44], lack of process standards [39; 45], and lack of proper ICT architecture [4] are more associated with technical challenges. Additionally, one of the common issues within organizations can be a misunderstanding of strategic importance