I'm thinking of things that satisfy these three criteria 1. Need to be configurable 2. Are meant to be used many times through an application 3. Are not easi

I'm thinking of things that satisfy these three criteria 1. Need to be configurable 2. Are meant to be used many times through an application 3. Are not easily built using regular html For point one, take a loot at input[type="text"] html5 elements for instance. Placeholders, validation, size, stylability, errors. Similarly, the video tag. Volume, play pause, size, quality, playback speed, compatible formats, much more. For point two and three, you could for instance make a Login component, to encapsulate your authentication form into a component, but this is easily achieved using regular html forms. Also, you're most likely only going to use it once or twice. So what are good examples? A sparkline component, this is a type of an inline graph. A markdown or html editor component. Custom interaction or input components. Consider for instance where you're working on an audio mixing application. A rotatableKnob element is an elementary input here.