Reactive search is a way of searching for things using feedback or responses to help make the search better. It's like playing "hot and cold" when you're looking for something hidden. When you're looking for a toy, your friend might tell you "hot" when you're close and "cold" when you're far away.
Reactive search works like this too. For example, if you're searching for something on the internet, instead of just putting in one search term and hoping for the best, you create a search that can change based on the feedback you get from the results.
Say you're looking for information about cats, but you realize that there are many types of cats and that you're interested in domestic cats. You can change your search term to "domestic cat" and get more specific results. If you see results that talk about cat food, you might add the word "health" to your search to find information about taking care of your cat.
Reactive search is like a puzzle that you piece together. The more feedback you get from your search results, the more you can adjust your search to get better results. Just like playing "hot and cold," it can take a little time, but the end result is worth it.