Union ∪

The Union character (∪) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ∪, the decimal numeric character reference ∪, or the hexadecimal numeric reference ∪. The character is assigned Unicode code point U+222A in the Universal Character Set.

The union symbol represents the set of all elements that belong to either of two or more sets. It is a fundamental operation in set theory, database queries (UNION), probability (combined events), and mathematical analysis. The symbol resembles the letter U.

Mathematical HTML entities enable web authors to display proper mathematical notation without relying on images or specialized rendering libraries like MathJax or KaTeX. While complex equations and multi-line formulas may still benefit from dedicated math typesetting tools, individual symbols expressed as HTML entities render quickly, remain accessible to screen readers, and can be styled with CSS just like regular text content.

When deciding how to encode the Union character in your HTML documents, the named entity ∪ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ∪ and hexadecimal form ∪ are equally valid alternatives that work in contexts where named entities may not be supported, or when generating HTML output programmatically from server-side code. All three representations produce identical visual output in every modern web browser.

Use the union symbol in set theory expressions (A ∪ B), database documentation explaining UNION operations, probability calculations for combined events, and educational content about sets. It is the set-theory counterpart to the logical OR operation.