This chapter provides the complete theoretical foundation required before any experiment in the manual can be meaningfully performed. It opens with the distinction between qualitative analysis (detecting what is present) and quantitative analysis (measuring how much), before introducing volumetric analysis and the central concept of titration. The law of chemical equivalence (N1V1 = N2V2) is derived and its significance explained: at the equivalence point, gram-equivalents of titrant and titrand are equal. The chapter then systematically covers all four principal titration types — neutralisation, oxidation-reduction (redox), precipitation (argentometric), and complexometric — with worked reactions for each. A detailed treatment of equivalent weight shows how the concept changes between acid-base, redox, and precipitation contexts. Standard solutions are classified as primary (prepared by direct weighing) or secondary (requiring standardisation), with criteria and examples for each. Concentration expressions — molarity, molality, and normality — are defined with calculation formulae and examples. The chapter concludes with the theory of pH, indicator selection, buffer solutions, and a section on double salts and complex compounds. Safety is woven throughout as a core analytical skill, and a table of common student mistakes closes the chapter.