Protein structure prediction involves computational methods to determine a protein's 3D structure from its amino acid sequence. Ab initio methods use physics-based calculations of potential energy to predict the most stable conformation. Comparative methods leverage databases of known protein structures, searching for sequences with similar folds. Homology modeling relies on the assumption that related proteins share similar folds, allowing prediction based on matches to distant evolutionary relatives. Protein threading compares local segments of the sequence to structural fragments in databases.