In CSS, the outline property is used to add an outline or border around an element. The outline property is often used to highlight an element. Outline property components: Outline-width Outline-color Outline-style Outline-width: This component sets the width of the outline. You can specify it using a length value (e.g., pixels) or use predefined keywords like thin, medium, thick, or auto. Outline-color: This component sets the color of the outline. You can specify it using color names (e.g., red, blue), hexadecimal color codes (e.g., #FF0000), RGB or RGBA values, or HSL or HSLA values. Outline-style: This component sets the style of the outline. It can take dotted, dashed, solid, double, groove, ridge, inset, outset, or none. These values define the pattern of the outline.