relAttribute

The rel attribute in HTML specifies the relationship between the current document and the resource linked by the element bearing the attribute. It is most commonly used on anchor (a), link, and area elements. The value of rel can contain one or more space-separated tokens, each indicating a particular relationship or instruction to the user agent.

Tokens define the nature of the link and how it should be treated. Common values include stylesheet (for linked CSS), author, help, license, next, prev, and alternate. In SEO contexts, nofollow instructs search engines not to follow the link. For security and privacy, the tokens noopener and noreferrer are used to mitigate reverse tabnabbing and to control Referer header behavior when linking with target="_blank". Performance hints such as prefetch and preload can be expressed to suggest fetching resources in advance.

The exact meaning of a given token can depend on the element. For example, rel="stylesheet" on a link element marks the linked resource as a stylesheet, while rel="nofollow" on an anchor signals that search engines should not pass ranking influence to the target. Multiple tokens can be combined, such as rel="noopener noreferrer" on a link with target="_blank".

Validation and compatibility: Browsers generally support a wide range of rel values, and unrecognized tokens are ignored. The rel attribute works with the HTML5 specification and is distinct from the deprecated rev attribute, which attempted to declare reverse relationships.

Examples: <a href="https://example.com" rel="noopener" target="_blank">Example</a> and <link rel="stylesheet" href="styles.css">.