The aim of this paper is to present the concept of software testing and to notice its importance in all phases of the software life cycle. In order to achieve this, it is necessary to get acquainted with the concept, its features, capabilities and limitations. Testing increases the probability of detecting software errors and, by correcting them, shortens the time of operation in faulty mode. Testing can be performed in a variety of ways, practicing one or combining multiple software testing methods. The emphasis in the paper was on the method of automated testing, which due to its simplicity excels over others. Atomized software testing aims to find system faults using the method of comparing the expected and actual results that the system further outputs for a particular input. The main advantage of this method is the reusability of test scripts, which results in reduced time required to test the software. In order to know which method to use as the primary testing method, it is necessary to have a good understanding of the functionalities of the system and its limitations because not every system can be tested with every testing method. The basic steps, methods, classes and processes for automated testing are presented on the example of a test script, which tests a part of a complex software system called Nais. Selenium was used as a tool for this practical example, while the script was written in the Java programming language.