Strong focusing is like when you use a magnifying glass to make something look bigger.
In a particle accelerator, we use magnets to help particles move around a tube in circles. These magnets are like really strong lenses that can focus the particles on a specific path. Just like a magnifying glass can make things look bigger by focusing light, the magnets in a particle accelerator can make particles move faster by focusing them in a certain direction.
This is important because the faster particles move, the more energy they have, and the more powerful they become. Strong focusing allows scientists to create more powerful particle collisions, which can lead to new discoveries and advancements in science.