To demystify the black-box approach to computing, we will start with an overview of computer architectures from a cluster down to microprocessor design. Topics such as vector registers and cache hierarchy will be discussed. Emerging architectures and accelerators such as GPUs and Xeon Phis will be introduced. Performance metrics such as FLOPs that are frequently used in the HPC community will be defined. Finally cloud computing and its advantages and disadvantages will be presented.