Strong acid + strong base: equivalence point at pH 7, steep curve near equivalence. Use methyl orange or phenolphthalein. Weak acid + strong base: equivalence point at pH > 7 (basic due to hydrolysis of conjugate base). Use phenolphthalein (pH 8-9.8). Strong acid + weak base: equivalence point at pH < 7 (acidic due to hydrolysis of conjugate acid). Use methyl orange (pH 3.1-4.4). Weak acid + weak base: equivalence point pH depends on Ka vs Kb; no sharp endpoint — no suitable indicator (potentiometric titration preferred). At the half-equivalence point of a weak acid-strong base titration, pH = pKa (because [HA] = [A-], so log(1) = 0 in Henderson-Hasselbalch). This is used experimentally to determine Ka values.