A phylogenetic tree is a diagram that represents the evolutionary relationships among various species or groups. It illustrates how different organisms are related through common ancestors, showing the branching patterns of evolution over time. Each branch point, or node, indicates a divergence where a single lineage splits into two or more lineages. These trees are constructed using data from various sources, including genetic information, morphology, and fossil records. By analyzing these data, scientists can infer the evolutionary history of species, helping to understand the process of evolution and the connections between different forms of life, such as plants, animals, and microorganisms.