Search engine indexing is like when you organize books on a bookshelf. A search engine collects and organizes all the information on the internet (like all the books in a library) and stores it in its “index” (like the bookshelf). Then, when you type something into the search engine (like the title of a book), it will look through its index and show you the most relevant results. By indexing all the websites, the search engine can quickly find the information you're looking for.