This chapter introduces the possibilities field-programmable gate arrays (FPGAs) currently offer in terms of field-programmable systems-on-chip (FPSoCs) design, with different hardware/software alternatives. It discusses the broader concept of systems-on-chip (SoC) and introduces the related terminology, which is closely linked to processor architectures. FPGAs have obviously also taken advantage of this technological evolution. In order for single-core architectures to cope with continuous market demands for faster, more computationally powerful, and more energy-efficient solutions, the only option would be to increase operating frequency and to reduce power consumption. The limitations of the aforementioned approaches can be overcome by using multicore processors, which integrate several processor cores on a single chip. Symmetric multiprocessing (SMP) architectures apply to homogeneous systems with two or more cores sharing memory space. They are based on using only one OS for all cores. In contrast to SMP, asymmetric multiprocessing (AMP) architectures can be implemented in either homogeneous or heterogeneous multicore processors.