BlockLevel

Blocklevel refers to elements that render as blocks in the normal document flow of HTML and CSS. A block-level element typically starts on a new line and stretches to the full available width, forming a distinct block on the page. Its height grows with content, padding, borders, and margins. Vertical margins between adjacent block-level elements can collapse, producing a cleaner vertical rhythm without double spacing.

Common block-level elements include structural and semantic containers such as p, div, section, article, header, footer, nav, aside, as well as h1–h6, ul, ol, li, blockquote, pre, and form. While these elements are often used for layout, their rendering is ultimately determined by the CSS display property; block and list-item are canonical block-level values, though an element’s display can be overridden to inline or inline-block if needed.

Inline-level elements contrast with block-level ones: elements like span, a, img, em, and strong render within a line and do not automatically start on new lines. They only occupy the width required by their content. Inline-block offers a middle ground, behaving like an inline element while accepting explicit width and height.

Block-level layout is foundational for page structure and responsive design. It supports stacking, spacing, and alignment in techniques ranging from traditional flow layout to modern approaches such as flexbox and CSS grid. Understanding block-level behavior helps in building accessible, orderly, and adaptable web content.