I think of computer indexed like a card catalog at the local library.

years ago libraries had a type of filing cabinet. Every book had a matching 3 X 5 paper in that cabinet and the papers were put in there alphabetically in one part, by author in another part and by subject. For example to find the book The courage to heal by Laura Davis The person would go to the cabinet and look in D for Davis Laura (author) C for Courage to Heal (title) H for healing (subjcet), R for Rape (subject contained in the book) S for Sexual abuse (subject contained in book) S for Self help (catagory of type of book) and so on.

A computer does the same thing. It files and keeps those files organized by subject, title, author, and so on.

Instead of the local library taking care of the files its google

A person can just by typing in one word in a search bar and see the results of every on line file that contains that word in it just like going to a library catalog cabiniet and looking for any words contained in the book they are looking for.