Google has been giving the line to the public that says they have over 200 signals they use as part of their ranking algorithm. Google is sticking with that, even after over ten years or so.
Google has of course added, removed, tweaked and modified many of those signals over the years. In fact, many signals have signals within them. So if you think of it, are you mobile friendly has various ways and signals to determine if a site is mobile friendly or not. This goes for all of Google's signals.
The line "over 200 signals" is because it is hard to define what is and isn't a ranking signal and because they are constantly tweaking it. There are core ranking signals, there are search quality signals, there are pure spam signals, there are UI changes, specific vertical signals and so much more - we didn't even mention the indexing and discovery aspect of URLs.
John Mueller said last week that Google will be sticking with the "over 200 signals" statement:
@jenstar @Skitzzo @methode I don't think I ever said 500 signals though, we tend to stick to our "over 200 signals" statement.
— John Mueller (@JohnMu) May 7, 2015Forum discussion at Twitter.
