Magnetic surveys are geophysical methods used to measure variations in the Earth's magnetic field. These surveys help identify subsurface features, such as mineral deposits or archaeological sites, by detecting changes in magnetic intensity caused by different materials. Data collected during magnetic surveys can be analyzed to create maps that reveal the distribution of magnetic anomalies. This information is valuable for industries like mining and oil exploration, as well as for researchers studying the Earth's geology and history. Techniques often involve using instruments like magnetometers to gather precise measurements over a designated area.