What is a geomagnetic storm and why a warning has been issued regarding it

On October 28th, a breathtaking Northern Lights display dazzled the northern United States residents after strong solar flare activity. The aurora borealis was visible from states such as Idaho, South Dakota, and New York. Issued by the National Oceanic and Atmospheric Administration, a Geomagnetic Storm Warning highlighted the heightened solar activity leading to this natural phenomenon.