The work to be presented in this book entitled "1,3,4-Thiadiazoles" is divided into 8 units. This book reports the strategic designing, synthesis and biological screening of title compounds wherein the biologically active [1,2,4]triazolo[3,4-b][1,3,4]thiadiazol scaffold is linked to potent chroman moiety. The present communication reports the strategic designing, synthesis, characterization and antimicrobial screening of novel 3-(6-Fluorochroman-2-yl)-6- aryl-[1,2,4] triazolo [3,4-b][1,3,4]thiadiazoles. Unit-1 deals with the General introduction of our research work, Unit-2 covers the Introduction, synthetic aspect and Therapeutic importance of thiadiazole derivatives. Unit-3 describes the Introduction, synthetic aspect and Therapeutic importance of Chromene derivatives. In Unit-4 Route of synthesis and reaction mechanism is given which includes the Reaction scheme and detailed pathway of reaction actually proceed. Unit-5 represents the experimental procedure. Unit-6 gives the Analytical data and spectral study which includes IR, 1H-NMR and Mass spectral data of all synthesised compounds. Unit-7 describes the Biological activity data of title compounds. Unit-8 covers references.