Greek Small Letter Psi ψ

The Greek Small Letter Psi character (ψ) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ψ, the decimal numeric character reference ψ, or the hexadecimal numeric reference ψ. The character is assigned Unicode code point U+03C8 in the Universal Character Set.

Psi is the twenty-third letter of the Greek alphabet, prominently used in quantum mechanics where it represents the wave function (ψ). It also denotes the digamma function in mathematics, water potential in plant biology, and is the symbol of psychology (Ψ). Its trident-like shape makes it visually distinctive.

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 Psi character in your HTML documents, the named entity ψ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ψ and hexadecimal form ψ 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 psi entity in quantum mechanics (wave function ψ), psychology (symbol of the discipline), and mathematics. It is essential for any web content about quantum physics, wave mechanics, or psychology. The uppercase Ψ is the recognized symbol of the field of psychology.