The paper provides an introduction to centrality measures in social networks, offering a new perspective based on relational algebra. It introduces the concepts of degree, closeness, betweenness, and flow indices, and discusses their implementation in computer programs CENTRAL and FLOWIND. The author defines these measures mathematically, emphasizing the distinction between directed and undirected relations, and local and global measures. The paper also explores network centralization measures, which assess the dominance of a single node in a network, and presents algorithmic aspects for computing these measures. An example using student government data is provided to illustrate the application of these indices.The paper provides an introduction to centrality measures in social networks, offering a new perspective based on relational algebra. It introduces the concepts of degree, closeness, betweenness, and flow indices, and discusses their implementation in computer programs CENTRAL and FLOWIND. The author defines these measures mathematically, emphasizing the distinction between directed and undirected relations, and local and global measures. The paper also explores network centralization measures, which assess the dominance of a single node in a network, and presents algorithmic aspects for computing these measures. An example using student government data is provided to illustrate the application of these indices.