Greek Small Letter Chi χ

The Greek Small Letter Chi character (χ) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference χ, the decimal numeric character reference χ, or the hexadecimal numeric reference χ. The character is assigned Unicode code point U+03C7 in the Universal Character Set.

Chi is the twenty-second letter of the Greek alphabet, most widely known through the chi-squared (χ²) statistical test. It also represents magnetic susceptibility in physics and the Euler characteristic in topology. Chi is the origin of the abbreviation 'Xmas' (X representing Chi, the first letter of Christ in Greek).

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 Chi character in your HTML documents, the named entity χ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form χ and hexadecimal form χ 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 chi entity in statistics (chi-squared test χ²), physics (magnetic susceptibility), and topology (Euler characteristic). The chi-squared test is one of the most commonly applied statistical tests, making this entity essential for data science and research methodology content.