Greek Small Letter Zeta ζ

The Greek Small Letter Zeta character (ζ) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ζ, the decimal numeric character reference ζ, or the hexadecimal numeric reference ζ. The character is assigned Unicode code point U+03B6 in the Universal Character Set.

Zeta is the sixth letter of the Greek alphabet, prominently used in the Riemann zeta function — one of the most important functions in number theory. It also represents damping ratio in control theory, electrokinetic potential in chemistry, and various other quantities in physics.

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 Zeta character in your HTML documents, the named entity ζ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ζ and hexadecimal form ζ 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 zeta entity in number theory content (Riemann zeta function ζ(s)), control systems engineering (damping ratio ζ), and chemistry (zeta potential). It appears frequently in advanced mathematics and the Riemann hypothesis, one of the most famous unsolved problems.