Reusable HTML elements
Let's think about HTML elements for a moment. Depending on the type of HTML element, it's either feature-centric or utility-centric. Utility-centric HTML elements are more reusable than feature-centric HTML elements. For example, consider the <section> element. This is a generic element that can be used just about anywhere, but its primary purpose is to compose the structural aspects of a feature: the outer shell of the feature and the inner sections of the feature. This is where the <section> element is most useful.
On the other side of the fence, you have elements such as <p>, <span>, and <button>. These elements provide a high level of utility because they're generic by design. You're supposed to use <button> elements whenever you have something that's clickable by the user, resulting in an action. This is a level lower than the concept of a feature.
While it's easy to talk about HTML...