Frameset

Frameset is an HTML element used to divide the browser window into multiple frames, each displaying a separate HTML document. It was popular in early web design, allowing a persistent navigation area while content changed in other frames. In HTML 4.x and XHTML 1.x, a document that uses frames includes a frameset element instead of a body element. The frameset element defines the layout with attributes such as cols and rows to specify how the window is partitioned. Within the frameset, one or more frame elements specify the source documents via the src attribute and can be named with the name attribute; other attributes include scrolling and frameborder (now deprecated). A noframes element can provide alternative content for browsers that do not support frames.

Each frame is its own browsing context loading its own document, so links can target a specific frame by name. Framesets can be nested to create complex layouts, but nesting increases complexity and can hinder accessibility and maintenance.

In HTML5, frameset and frame elements are obsolete and have been removed from the standard; modern web design favors CSS-based layouts and the iframe element for embedding external content where appropriate. Many browsers still support frames for legacy sites, but they are generally discouraged for new development due to usability, bookmarking, and search-engine indexing concerns.

Example: a two-column frameset with a navigation frame on the left and a content frame on the right uses a frameset element with cols="25%,75%" and two frame elements with src attributes; a noframes section provides text for environments that do not support frames.