The history of pharmaceuticals is as old as humans are. Traditional practitioners had used drugs in one or another form in ancient times. Then came the era of traditional dosage forms including the most common and famous dosage forms e.g. tablets, capsules, syrups, etc. These dosage forms were unable to deal with the prolonged effect required, especially, when multiple frequencies of a single drug were required in a day. This originated the concept of digging new areas in the vast field of pharmaceutics. Therefore, an idea to fabricate controlled release dosage forms went through one's head. This was a paradigm change in the arena of pharmaceutical technology from conventional to controlled release formulations.Controlled release systems are one of the powerful tools used in advanced drug delivery systems. There are different technologies used to prepare controlled release systems. Polymeric matrices, ion-exchange systems, and osmotically controlled systems are a few examples of sustained-release systems. These systems along with some more technical floating systems have been discussed here in this book, keeping pharmacy students new in the arena. Therefore, this book will accomplish the thirst of students and researchers.