A single-core processor is a type of computer chip that has only one core, meaning it can execute one instruction at a time. This design was common in early computers and is simpler and less expensive to produce. However, it limits the processor's ability to handle multiple tasks simultaneously, which can slow down performance when running demanding applications. In contrast to multi-core processors, which have multiple cores that can work on different tasks at the same time, single-core processors are less efficient for modern computing needs. They are often found in basic devices like older smartphones and simple embedded systems, where high performance is not a priority.