Greek Small Letter Omicron ο

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

Omicron is the fifteenth letter of the Greek alphabet and is visually identical to the Latin letter 'o.' Because of this visual similarity, omicron is rarely used in mathematics and science — other Greek letters are preferred to avoid confusion. It gained public recognition during the COVID-19 pandemic as a variant name.

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 Omicron character in your HTML documents, the named entity ο is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ο and hexadecimal form ο 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Use the omicron entity in content about the Greek alphabet, linguistics, and historical references. In scientific notation, omicron is typically avoided in favor of other Greek letters or the Latin 'o' due to their visual identity. In computer science, capital O (Big O notation) is technically Latin, not Greek omicron.