Prime ′

The Prime character (′) is a standard HTML entity defined in the HTML specification. In HTML source code, it can be written using the named entity reference ′, the decimal numeric character reference ′, or the hexadecimal numeric reference ′. The character is assigned Unicode code point U+2032 in the Universal Character Set.

The prime symbol is a straight, slightly angled mark used to denote feet in imperial measurements, arcminutes in angular measurement, and first derivatives in mathematical notation. It is distinct from the apostrophe and the right single quotation mark, though they are frequently confused in digital text.

Punctuation and whitespace entities are among the most frequently used HTML entities in web development. They handle characters that either have special meaning in HTML syntax — such as angle brackets and ampersands — or represent typographic characters that improve the visual quality of text, like em dashes and curly quotes. Proper use of punctuation entities is essential for producing valid, well-formed HTML documents and achieving professional-looking typography on the web.

When deciding how to encode the Prime character in your HTML documents, the named entity ′ is generally the most readable choice for developers reviewing or maintaining source code. The decimal form ′ and hexadecimal form ′ 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 prime symbol for feet in measurements (5′), arcminutes in coordinates (40° 26′ N), and derivatives in calculus (f′). Do not use the straight apostrophe or curly quote as substitutes — the prime is the technically correct character for these scientific and mathematical contexts.