Pajek is a program package for Windows (32-bit) designed for the analysis and visualization of large networks (with thousands of vertices). Developed by Vladimir Batagelj and Andrej Mrvar, Pajek supports various data types including networks, partitions, clusters, vectors, permutations, and hierarchies. Key features include efficient algorithms for analyzing large networks, powerful visualization tools, and support for 2-mode and temporal networks. Pajek is widely used in social network analysis, chemistry, genealogies, Internet networks, citation networks, and data mining. It is also used in academic settings for teaching network analysis courses. The software offers automatic and manual layout algorithms, supports non-native input formats, and can export layouts in multiple graphic formats. Pajek is implemented in Delphi and runs on Windows 32-bit operating systems.Pajek is a program package for Windows (32-bit) designed for the analysis and visualization of large networks (with thousands of vertices). Developed by Vladimir Batagelj and Andrej Mrvar, Pajek supports various data types including networks, partitions, clusters, vectors, permutations, and hierarchies. Key features include efficient algorithms for analyzing large networks, powerful visualization tools, and support for 2-mode and temporal networks. Pajek is widely used in social network analysis, chemistry, genealogies, Internet networks, citation networks, and data mining. It is also used in academic settings for teaching network analysis courses. The software offers automatic and manual layout algorithms, supports non-native input formats, and can export layouts in multiple graphic formats. Pajek is implemented in Delphi and runs on Windows 32-bit operating systems.