Process mining is a set of data analysis techniques and tools for extracting information from so called event logs which are commonly available in modern IT systems. Event logs register activities performed by an organization's employees. Such logs are typically created, inter alia, in document workflow systems, customer relationship management systems, task management systems. Because information systems support the operation of many areas of an organization, event logs record its real manner of operation. Real, in other words not presumed. Process mining joins ideas of process modelling and analysis on the one hand and data mining and machine learning on the other. Well-performing organisation consists of individuals collaborating together in some social context to achieve common and individual goals. To achieve those goals effectively organisations must address the challenges of dynamic, turbulent and competitive environment. This leads to constant, ongoing change in working methods, methods of goods and service delivery etc. Knowledge about real shape of business processes is a first step to perform such a change effectively. The two characteristics of process mining facilitate efficient change in organization and distinguish process mining from other data analytic techniques: (1) focus on people and their decisions, interactions, collaboration patterns and organizational dependencies, (2) focus on activities performed by those people and casual and time dependencies among those activities.