Greek Small Letter Delta δ

The Greek Small Letter Delta character (δ) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference δ, the decimal numeric character reference δ, or the hexadecimal numeric reference δ. The character is assigned Unicode code point U+03B4 in the Universal Character Set.

Delta is the fourth letter of the Greek alphabet and represents change or difference in mathematics and science. Lowercase delta (δ) is used for small changes, the Kronecker delta function, and the Dirac delta function. It is one of the few Greek letters whose meaning is widely understood outside academic contexts.

Greek letter entities are indispensable for scientific papers, engineering documentation, statistical analyses, and mathematical content published on the web. From physics equations using alpha and omega to statistical formulas featuring sigma and mu, these entities allow content authors to include Greek characters reliably without requiring specialized fonts or complex Unicode input methods on the keyboard.

When deciding how to encode the Greek Small Letter Delta character in your HTML documents, the named entity δ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form δ and hexadecimal form δ 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 lowercase delta in mathematical expressions for infinitesimal changes (δx), the Kronecker delta (δᵢⱼ), and physics notation. For the 'change in' or 'difference' meaning commonly seen in finance and engineering, the uppercase Δ (capital delta) is more conventional.