Indexing is the stage where Google processes a page it has found and stores it in the Google index — the massive database it draws from to build search results. Only pages that are in the index are eligible to appear when someone searches.
It helps to see where indexing sits in the sequence. First Google has to find your page (crawling). Then it has to understand and store it (indexing). Only then can it be chosen and ordered among results (ranking). Indexing is the middle gate everything else depends on — a brilliant page that never gets indexed is invisible.
