This chapter illustrates an introduction to the field of Supramolecular chemistry, host-guest chemistry, and aggregation. Formerly Supramolecular chemistry was regarded as host-guest chemistry. It tells the reader that at present, supramolecular chemistry encompasses not just host-guest systems but also self-assembly, aggregation, folding, molecular recognition, dynamic covalent chemistry, and nanochemistry. Next, the introduction of the aggregation of luminophores in supramolecular systems is demonstrated. The evolution of the field is examined through thermodynamics, kinetics point of view, and relevant historical examples as well as those that elucidate exciting aspects of the aggregation process or its potential applications. Using supramolecular aggregates from building blocks with easy design and facile syntheses could accomplish even better sensing performance than that of molecular sensory systems that rely on sensors with delicate structures. Finally, the discrimination between aggregation and self-assembly is illustrated, because generally readers get confused with both the terminology. Finally, conclusions and future scope are presented and discussed.