Google’s Danny Sullivan confirmed a Google algorithm update on Twitter. He said that Google does focused updates nearly daily. Broad core algorithm updates happen several times per year:
Yes, see here: https://t.co/gckGCFT9tJ— Danny Sullivan (@dannysullivan) 12. März 2018
We do some type of focused update nearly daily. A broad core algorithm update happens several times per year.— Danny Sullivan (@dannysullivan) 12. März 2018
Focused updates are minor updates that deal with a single issue (page speed, HTTPS, etc.). Core updates address multiple things (such as the Panda update or the Penguin update).
How to react to the ranking algorithm update
If your website hasn’t seen a ranking drop, you don’t have to do anything. You can check the rankings of your website with the Ranking Monitor tool in SEOprofiler. If your rankings have dropped, use the website audit tool and the Top 10 Optimizer tool in SEOprofiler to improve your pages so that they can get better rankings