A single-core processor is a type of computer processor 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 manufacture. 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 can handle several tasks at once by using multiple cores, single-core processors are less efficient for modern computing needs. They are often found in basic devices like older laptops, simple desktops, and embedded systems where high performance is not a priority.