Transdermal drug delivery systems were developed in order to overcome the difficulties associated with oral drug delivery. Through an adhesive patch affixed to the skin, transdermal patches deliver medications into the bloodstream. This treatment may benefit damaged areas of the body. Unlike oral, topical, intramuscular, and intravenous drug delivery methods, transdermal drug delivery enables controlled drug release into the body. Body heat is used to melt thin layers of medication embedded in the adhesive through the transdermal patch's porous membrane. As a barrier against foreign invaders, the skin serves as a protective layer. A medication with a molecular weight less than 500 Da can penetrate the stratum corneum through the outermost layer of the skin. An overview of transdermal patches is provided in this review article, including matrix patches, reservoir patches, membrane patches, micro reservoir patches, and patches that contain drugs in adhesive forms. These dosage forms have also been evaluated using various methods.