The li HTML element is used to represent an individual item within a list, whether ordered (ol) or unordered (ul), contributing to the structured presentation of grouped content.

The main HTML element is used to encapsulate the dominant content of a document, excluding headers, footers, and sidebars, to improve accessibility and SEO by clearly defining the primary content area.

The map HTML element is used to define an image map, a collection of clickable areas on an image, in conjunction with area elements. Each area can link to different destinations, allowing for interactive images.

The mark HTML element is used to highlight text within a document, indicating relevance or importance, typically rendered with a yellow background by default.

The menu HTML element was intended to define a list of commands or options, such as context menus or toolbars. However, its use is largely obsolete, and it is not widely supported in modern browsers.

The meta HTML element is used to define metadata about an HTML document, such as character set, description, keywords, and viewport settings. This metadata is crucial for search engines, browsers, and web services to interpret and display content.

The meter HTML element is used to represent a scalar measurement within a known range or a fractional value, such as disk usage or voting percentages. It visually displays this data as a gauge, with attributes to define the range and current value.

The nav HTML element is used to define a set of navigation links, typically for a website's main navigation menu. It helps organize and structure the navigation of a webpage, improving accessibility and user experience.

The noscript HTML element is used to provide alternative content for users whose browsers do not support JavaScript or have scripting disabled. It ensures that essential information or functionality is accessible even without scripts.

The object HTML element is used to embed external resources, such as images, videos, or interactive content. It can also serve as a container for plugins or other applications, offering flexibility in integrating diverse media types.