This document provides an overview of next generation sequencing (NGS), including its history, key methods, applications and challenges. It discusses that NGS allows for massively parallel sequencing of thousands of DNA molecules simultaneously, providing exact sequences of genes. Some main NGS platforms and their sequencing methods are described, such as Illumina sequencing by synthesis. Applications of NGS discussed include cancer research, pharmacogenetics and preimplantation genetic diagnosis. Challenges associated with NGS like poor quality FFPE samples and large data analysis workflows are also outlined.