Geomagnetically induced currents, affecting the normal operation of long technological conductor systems, are a manifestation at ground level of space weather. During space weather events electric current systems in the magnetosphere and ionosphere experience large spatiotemporal variations reflected also in the variations of the Earth's geomagnetic field. These variations induce currents in conductors operated at the surface of Earth. Electric transmission grids and buried pipelines are common examples of such conductor systems. GIC can cause problems, such as increased corrosion of pipeline steel and damaged high-voltage power transformers. GIC are one possible consequence of geomagnetic storms, which may also affect geophysical exploration surveys and oil and gas drilling operations.