This document discusses national innovation systems (NIS) from an institutional perspective. It outlines the development of the concept of NIS and defines it as a network of institutions involved in technology development and diffusion within national borders. A systemic approach views innovation as an interactive and cumulative process involving industry, universities, government and other actors. Institutions play key roles in NIS by providing information, managing conflicts, incentivizing innovation, and channeling resources. The functions and components of NIS vary across countries due to different socioeconomic and cultural contexts.