Last year alone, over 3,200 changes were made to Google’s search system. This came out of Google’s blog post on keeping its search results relevant and useful.
On average, Google makes a number of changes to search every day, and the 3,200 would equate to several a day. Google wrote, “Our search algorithms are complex math equations that rely on hundreds of variables, and last year alone, we made more than 3,200 changes to our search systems.”
Back in 2010, Google had about one change per day. Matt Cutts, who used to be Google’s search spam fighter, said Google made about 350-400 changes in 2009. Google has expedited those changes over the years.
The changes made to the search system seems to be a mix of ranking and interface changes. According to Google, “Some of these were visible launches of new features, while many others were regular updates meant to keep our results relevant as content on the web changes.”
“And some are also improvements based on issues we identified, either via public reports or our own ongoing quality evaluations,” Google added.
Changes takes time for Google. Although knowledge panel and auto-suggestion predictions can happen quickly, features snippets and other changes that focus on the core web results take time.
Google said, “Unlike with Search features where we are able to quickly correct issues that violate our policies, sometimes identifying the root cause of ranking issues can take time, and improvements may not happen immediately.”
NOTE: It seems that this information is a few months old and in the past few months Google updated the How Search Works page with 2017 numbers.