The joining technology of similar and dissimilar materials plays a crucial role in various areas, include manufacturing. Many conventional welding techniques have been used over the years to successfully join various materials. Friction stir welding (FSW) and friction stir spot welding (FSSW) are solid state welding processes. This introduction gives a brief overview of the two processes, with the focus on FSW and FSSW between copper and aluminium, which are sometimes difficult to join by using conventional joining methods because of their different melting temperatures and their high chemical affinity. Furthermore, the applications of FSW and FSSW in various industrial sectors include robotics, aerospace and automotive areas. An overview of the experimental studies conducted in joining aluminium and copper was conducted. It was observed that FSW and FSSW of aluminium to copper has not yet been fully researched; but more studies are needed for FSSW, in order to optimize the process, which could lead to its expansion.