If you noticed a change in your site's search engine ranking or the traffic it receives, a recent algorithm update from Google is likely the cause. On March 12th, Google launched, what it has dubbed the "March 2019 Core Algorithm Update". As with any update, the changes will have an effect on the SEO of most sites.
Google regularly updates its algorithm, and in many cases, they don't announce the update or what has been changed. SEO experts usually notice these algorithm updates when there is a significant shift that is impacting every site. In this situation, Google confirmed the update after receiving questions about the changes online.
Unfortunately, besides confirming that the update took place, Google hasn't provided any guidance on what has changed. This omission isn't unusual. Google rarely explains how an algorithm has changed, except in cases where they are trying to drive a specific behavior, such as promoting mobile responsiveness or the adoption of HTTPS.
Early data from SEO researchers haven't shown anything that's hugely different from before. In fact, some are treating this update as more of a downgrade from previous algorithm updates. This perspective is based on the fact that many of the sites that went down in previous updates saw their rankings improve. This movement suggests that the new update rebalances some past changes to make them more equitable.
Google referred users to some of its previous advice on updates, which stated, "Each day, Google usually releases one or more changes designed to improve our results. Some are focused around specific improvements. Some are broad changes. Last week, we released a broad core algorithm update. We do these routinely several times per year. As with any update, some sites may note drops or gains. There's nothing wrong with pages that may now perform less well. Instead, it's that changes to our systems are benefiting pages that were previously under-rewarded."
A common question after any Google algorithm update is "How can I fix my site?" To Google, this is the wrong question to have. As Google stated in its previous advice on algorithm updates, "there's no 'fix' for pages that may perform less well other than to remain focused on building great content. Over time, it may be that your content may rise relative to other pages."
This response may not be the most comforting to website owners, but the advice is correct. Continually adding new content to your website that matches what your target audience is searching for is always the best SEO strategy. Google's algorithms are designed to find content that matches the queries of users. You increase the likelihood of getting a high ranking by increasing the amount of high-quality content you have on your site about a specific subject matter.
If you see that your website has dropped in rankings, consider adding a series of new, high-quality blog posts about your industry to give Google new content to index for your site.
For more recent news about Google updates and changes, read this article on Google's recent redesign involving accounts on Google My Business.