To address the challenges associated with oral drug delivery, a transdermal drug delivery system was developed. To deliver a specific dosage of medication through the skin and into the bloodstream, a transdermal patch is an adhesive patch that has been medicated and applied to the skin. This frequently encourages a body part that has been injured to heal. The capacity to regulate medicine to a understanding in a controlled way by means of a transdermal fix is one advantage over other strategies, such as verbal, topical, intravenous, intramuscular, etc. Typically, this is achieved by either a porous membrane enclosing a drug reservoir or by body heat melting thin layers of medication embedded in the adhesive. As a result, only drugs whose molecules are small enough to pass through the skin can be administered via transdermal delivery systems. This is the main drawback of these systems. The preparation processes for several transdermal patch types, including matrix patches, reservoir types, membrane matrices, drug-in-adhesive patches, and micro-reservant patches, are covered in this review article. Furthermore, reviewed have been the numerous techniques for assessing transdermal dosage forms.