The condensation reaction can occur in acidic, basic conditions or in the presence of other catalysts. This type of reactions is an essential part of our life as it is an important to form peptide bonds in between amino acids in protein and the biosynthesis of fatty acids. This chapter provides valuable information on reaction details, step-by-step mechanism, experimental procedures, applications, and (patent) references of some named condensation reactions. The reactions covered are Aldol condensation reaction, Mukaiyama Aldol reaction, Evans Aldol reaction, Henry reaction, Benzoin condensation, Claisen condensation, Darzens Glycidic ester condensation, Dieckmann condensation, Knoevenagel condensation, Pechmann condensation, Perkin condensation, and Stobbe condensation.