Automatic indexing is like having a helper who sorts all your toys for you without you having to lift a finger. When you have a lot of toys, it can be hard to find the one you want to play with. But if you have a helper who sorts your toys into different categories, like cars, dolls, and blocks, it becomes a lot easier to find what you're looking for.
Similarly, when you have a lot of information in a big document or website, it can be hard to find the specific thing you're looking for. But with automatic indexing, the computer does the sorting for you! The computer looks at all the words and phrases in the document or website and creates a list of them, kind of like an index in the back of a book.
This makes it easier for people to quickly find what they need without having to read through the whole document or website. For example, if someone is looking for information about dogs, they can look at the index and find all the places in the document or website where the word "dog" appears. This saves time and frustration, just like having a toy helper to help you find what you're looking for!