What It Is
A WordPress website is built from many pieces of software, including WordPress itself, your theme, each plugin, and the programming language (PHP) running on the server. Their developers release updates regularly. Some add features, but many quietly fix security problems that have been discovered. Updating is like getting the recall repairs done on your car: easy to put off, but the issue does not go away on its own.
Why It Matters for Your Business
Most hacked small-business sites were not targeted personally. They were found by bots scanning for a known flaw in an outdated plugin. Once a fix is published, the flaw is public knowledge, so sites that wait are easy targets. Updates also keep your site compatible with newer browsers and newer server software, which helps prevent strange errors down the road.
Good to Know
Update regularly, but do it carefully. Make a backup or restore point first, update one item at a time when possible, and check key pages like your contact form and checkout afterward. Delete plugins and themes you are not using, since they can still be exploited even when switched off. If you never have time, a managed WordPress hosting plan can handle updates for you.