CSS Outlines
CSS Outlines are a visual styling property in CSS that draws a line around elements, similar to borders but with key differences: they do not take up space in the layout (they are drawn outside the element's border edge) and are often used for accessibility purposes like focus indicators. They are defined using properties such as outline-width, outline-style, outline-color, and the shorthand outline, allowing developers to customize the appearance without affecting the document flow.
Developers should learn and use CSS Outlines primarily for enhancing accessibility, as they provide visible focus indicators for interactive elements like links and form inputs, which is crucial for keyboard navigation and screen reader users. They are also useful for debugging layouts temporarily, as they can highlight elements without disrupting the box model, and for creating non-intrusive visual effects in designs where borders would alter spacing.