I want to know why my website pages indexing keeps on changing in Google.com. Earlier when i was checking my website page indexing on weekly basis by typing site:www.example.com it did not vary by more difference but now a day when i am checking it, its vary by large difference. Around two week ago my website pages was around 25,000 but last week when i checked it showed me around 9000 indexed page and today when i checked it, it showed me around 16,000. I don't know why this is happening. Please help and provide me exact reason.