Block-level elements are rectangular and stack on top of each other, preventing other elements from sharing the same line. This behavior is controlled by the CSS property display: block.

Key points about block-level elements:

• They default to display: block;
• Their width spans the full width of the parent container;
• Their height is determined by the content but can be customized with CSS;
• They always start on a new line;
• Properties like border, margin, padding, width, and height can be adjusted.

Let's explore an example where we manipulate width, height, and margin:

Let's consider how we can center an element inside its parent.