At equivalence point: milliequivalents of acid = milliequivalents of base. N1V1 = N2V2, where N = normality = M x n-factor. Alternatively: M1V1n1 = M2V2n2 (using molarity and n-factors). Types: (1) Acid-base titration: strong acid + strong base, using phenolphthalein or methyl orange. (2) Redox titration: KMnO4 (self-indicator, purple to colourless in acidic medium), K2Cr2O7, iodometric (Na2S2O3 with starch indicator). (3) Back titration: add known excess reagent to sample, titrate the unreacted portion. Used when: sample is insoluble, reaction is slow, or direct titration endpoint is unclear. (4) Double titration: NaOH + Na2CO3 mixture with HCl — phenolphthalein endpoint gives NaOH + 1/2 Na2CO3, methyl orange endpoint gives total acid used.