The lecture, titled "A Brief Introduction to GNSS," expounded on Global Navigation Satellite Systems (GNSS). All major areas of the topic were covered, from its definition and importance to its past and present. The lecturer noted the significance of some older systems of navigation, such as dead reckoning navigation, celestial navigation, and radio navigation, which later became the building blocks for the more recent systems used today. With the emergence of GNSS, scientists developed more advanced and accurate navigation systems, namely GPS, GLONASS, GALILEO, and BEIDOU. Although GNSS is the most advanced form of navigation we have thus far, it still has some issues. One of the leading causes of errors in navigation systems is the ionosphere. That is why studying these errors and finding solutions is the main focus of the Space Weather and Ionosphere Lab at SASST.