This work provides a thorough overview of state of the art of stability of perovskite solar cells (PSCs) and covers important degradation issues involved in this technology. Degradation factors, which are reported in the literature affecting the stability of PSCs, are discussed. Several degradation mechanisms resulting from thermal and chemical instabilities, phase transformations, exposure to visible and UV light, moisture and oxygen and most importantly sealing issues are thoroughly analyzed. Methods are suggested to study most of these degradation mechanisms in a systematic way. In addition, environmental assessment of PSCs is briefly covered. Alternative materials and their preparation methods are screened with respect to stability of the device. Overall, this work contributes in developing better understanding of the degradation mechanisms and help in improving overall stability of the PSCs.