Basically, if you only built your site with the Core features of Word Press, and used only the default themes that Word Press is shipped with, then you could update your website without any fear of any negative impact.
Word Press Core contributors follow a consistent methodology. This is called “backward compatibility” and it’s one of the most important features of Word Press, one that sets it apart from all other CMS’s.
Thousands of people have contributed to the code, and new contributors from around the world are added every new release.
Some people wonder why they have to update their Word Press Core so often. Furthermore, the improvements in the code are real.
What this means: When you have trouble with your Word Press updates, it isn’t because of Core, it’s because of the third-party plugins and/or themes that you are using on your website.For example, Bob Dunn at Bob posted his experience in updating 100 plugins with the Word Press 4.0 update. Most likely, you’re saying to yourself: “Who just uses Word Press Core without plugins or themes? So how do we responsibly update our Word Press website considering all the plugins and themes that we all rely on?