Google are supposed to make changes to their search algorithm around 500 to 600 times a year, so even when you think that you have it mastered it can change.
Of course, these changes are only going to be tiny in the scheme of things. Yet even when it comes to the bigger picture, a small change in the search algorithm can make all the difference.
Website owners may think that the Google search algorithm is everything and maybe for some owners it is, for those who worry about it this graphic from Outrider shows how the Google search algorithm has changed over the years.
Source [Techie Bros]