Understanding the magnetic environment of our planet and the geomagnetic field changes in time and space is a very important issue for assessing the Sun-Earth interactions. All changes in solar activity impact the delicate balance between influences of interplanetary magnetic field and of geomagnetic field. The most dynamic events eventually result in disturbances in the magnitude and direction of the Earth's magnetic field and therefore impact our planet and its magnetosphere as a whole. The dynamics of the ionosphere and thermosphere during magnetic storms and substorms involves the heating, expansion, and composition changes at high latitudes, but also the surface-level response in terms of geomagnetically induced currents and other geomagnetic and geoelectric disturbances. Here, we provide a short overview of the current knowledge of the Earth's magnetic field, its present shape and the way it responds to external forces. The main aim of the paper is not to present the complexity of the space weather processes, but rather to bring the attention of the geohazard community to the possible dramatic effects of space weather events. For this, the paper highlights some societal implications of space weather on our increasingly technology-dependent society, including some possible effects of geomagnetically induced currents, the disruption of satellite communications and navigation, and risks of radiation damage both in space and in aviation.