This document defines the basic terms used in CSS style sheets. It explains that a CSS rule contains a selector and declaration block, where the declaration block contains property-value pairs defining aspects like color and font-size for the selected element. It notes that a declaration is a property-value pair ending in a semicolon, and multiple declarations make up a declaration block surrounded by curly braces.

1. h1 { color: #333; font-size: 30px; }
RULE
Selector Declaration Property Value
Declaration box

2. h1 {
color: #333;
font-size: 30px;
}
 Property- Describes an aspect of an elements presentation,
such as color, or font-size.
 Value- Descriptor defining a specific appearance, such as
color name or measurement.
 Declaration- A declaration is a property-value pair. Every
declaration should end with a semi-colon.
 Declaration Block- Set of declarations grouped together.
Always surrounded by curly braces {}
 Selector- Defines the elements of a document.