Yes, it’s true. Essentially what this means is that every day, Google is making minor, or major tweaks to what they consider to be essential ranking factors for websites appearing on Google. The algorithm is basically a recipe that contains the ingredients necessary to prepare a crowd pleasing meal, aka the search results. Some of the key ingredients include the integrity of the website, words that appear on pages, how people are linking to other pages, and many more.
The minor tweaks happen every day and can be equated to changing an ingredient in a recipe such as an extra punch of salt here and an extra drop of hot sauce there which alter the end result but sometimes are only noticeable to the trained “palate”. The larger changes known as “updates” happen less frequently but usually have an immediate noticeable impact. These “updates” would be more like receiving a well done ribeye steak when you were expecting medium rare. You notice the difference as soon as you cut into it, if not sooner.
All this implies is that we have to be aware and accepting of the fact that Google changes its algorithm all the time and this can cause sites to rise and fall, sometimes with no apparent method to the madness. It’s simply a matter of Google constantly trying to improve itself. The other important point to keep in mind is that Google has no set schedule for making these changes and “updates”. They are about as unpredictable as life itself. Check out Google Panda Update: Google Confirms New One, for a more in depth look at one of Google’s recent updates.