Phosphorylation is one of the most extensively studied post-translational modifications, playing a central role in regulating protein function and a wide range of cellular processes. Due to its involvement in the broad spectrum of cellular functions, prioritizing and annotating functional phosphorylation sites is of utmost importance, the task hindered by a significant fraction of sites being non-functional. The thesis will describe multiple approaches for predicting functional sites, including conservation, involvement in cross-talk with other post-translational modifications, location of the phosphosite on 3D protein structure and others. The student will also take advantage of recently predicted functional scores for human phosphosites to compare the functionality of sites coming from low- and high-throughput studies.