Google has confirmed a broad core algorithm update rolled out the first week of August. Broad core updates tend to have large affects on web rankings as a whole, rather than focussing on smaller matters that Google might be tweeking on a daily basis.
Google confirmed Wednesday on Twitter that it released a “broad core algorithm update” this week. This was after the search community noticed shifts in rankings and traffic earlier this morning. Google will release several algorithm updates per year that it may confirm, while many others are not confirmed or recognized by Google.