 Transparent conducting oxides, TCOs, are electrically conductive materials with low absorption of light within the visible spectrum. These materials are typically prepared using thin film technologies and are used in optoelectronic devices such as solar cells, displays, optoelectric interfaces and circuits. In this paper, we provide an overview of recent developments in the field of TCOs focusing on N-type TCOs which are important for thin film solar cell production. We discuss indium tin oxide, ATO, and aluminum doped zinc oxide, ZNO, AL, two commonly used materials, and their properties, preparations and applications. Additionally, we also cover P-type delifosate TCOs which have been gaining popularity recently. Finally, we provide a list of references for further reading. This article was authored by Andreas Stadler.