Transdermal drug delivery system (TDDS) is topically administered dosage form in the form of patches which deliver drugs for systemic effects at a predetermined and controlled rate. It works very simply in which drug is applied inside the patch and it is worn on skin for long period of time. By this constant concentration of drug remain in blood for long time. Polymer matrix, drug, permeation enhancers are the main components of TDDS; Polymers include gelatine, gum Arabic, methyl cellulose, starch, shellac, etc. (as a natural) to synthetic ones (polyethylene, polystyrene, acetyl co-polymer, polyvinyl chloride, polyamide, polyvinyl acetate, etc.) TDDS are of many types varying from single layer drug in adhesive to multi layer drug in adhesive and others are reservoir and the matrix systems. The market value of TDDS products are increasing with rapid rate, more than 35 products have now been approved for sale in US, and approximately 16 active ingredients are approved globally for use as a TDDS. Transdermal drug delivery is a recent technology which promises a great future it has a potential to limit the use of needles for administering wide variety of drugs but cost factor is a important thing to consider since developing nations like INDIA have second highest population, but due to higher cost TDDS are the hidden part of therapy used in general population. This review article provides an overview of TDDS, its advantageous and disadvantageous, basic components, types, evaluation and recent trends.