What is Google algorithm update?

Google changes its ranking systems constantly, and most changes go unannounced. A few times a year it confirms a broad core update, and those are the ones that move enough traffic for people to notice.

After a drop, resist the urge to change everything at once. Wait until the rollout finishes, then compare which pages and which keywords lost ground. A sitewide slide and a slide on ten thin pages call for different responses.

No site is update-proof. The pages that hold up tend to have a named author, first-hand detail nobody else has, and an honest match to what the searcher actually wanted.