HTML实体参考

What an HTML entity is, and why you need one

An HTML entity is a short code that stands in for a character a browser would otherwise misread or fail to display. A few characters are structural in HTML — the browser treats them as markup, not text. The clearest example is the less-than sign: write < directly in your page and the browser starts looking for a tag. To show a literal < on screen you must write the entity < instead. Entities also let you type characters your keyboard can't produce — a Greek π, an em dash —, a copyright ©, or an arrow → — without hunting for special key combinations or pasting from another app. This reference lists hundreds of them across categories, and clicking any code copies it straight to your clipboard.

Three ways to write the same character

Most characters can be expressed three ways, and the table shows all three side by side:

All three render identically. The key practical difference: not every character has a named entity. The euro and copyright signs do, but a Bitcoin sign, an Indian rupee, or most emoji-style symbols do not — for those, this reference shows a dash in the "Named" column and you must use the numeric or hex form. Numeric and hexadecimal forms always work because every character in Unicode has a code point.

The five entities you actually must memorise

Out of the hundreds listed, only a handful are non-negotiable when you generate HTML by hand or in code. Whenever you insert untrusted or user-supplied text into a page, escape these to prevent broken layout and cross-site scripting:

• & for the ampersand & — escape it first, or it can swallow the entities that follow it.
• < and > for < and > — these stop text from being parsed as tags.
• " for the double quote " — needed inside double-quoted attribute values.
• ' for the apostrophe ' — needed inside single-quoted attributes. (The named form ' works in HTML5 but not in older HTML 4, so the numeric form is the safer choice.)

A worked example: a "less-than or equal" comparison

Suppose you're documenting a rule that reads "price <= 100". Typed raw into HTML, the < would begin a phantom tag and the rest of the line could disappear. Search this reference for "less" and you'll find two relevant rows: < for the plain less-than sign, and ≤ (numeric ≤) for the proper "less-than or equal to" symbol ≤. Writing price ≤ 100 renders as the clean, correct price ≤ 100 — both safer and more professional than the ASCII <=.

The non-breaking space, the most misused entity

  renders as a space, but it has a special property: the browser will never break a line at it, and it won't collapse the way ordinary repeated spaces do. Use it to keep a number with its unit (10 kg) or a name with a title together on one line. The common mistake is reaching for a string of     to create indentation or layout gaps — that's fragile and inaccessible. Use CSS margins and padding for spacing; reserve   for genuinely non-breaking text.

Search tips and practical use

• Search by description, name, or the character itself. Type "arrow" to see the whole arrow family, "copyright" to find ©, or paste the symbol directly to discover its codes.
• Browse by category when you're exploring. The tabs group entities into Basic, Currency, Mathematical, Greek, Arrows, Punctuation, Latin Extended, and Symbols — handy when you know roughly what you want but not its name.
• Prefer typographic punctuation. Real curly quotes (“ “ &rdquo; ”) and proper dashes (— —, – –) look far more polished than straight quotes and hyphens.
• Modern pages are UTF-8. If your document declares a UTF-8 charset, you can often paste the character directly. Entities remain the bullet-proof choice for the five structural characters and for email or legacy systems where encoding is uncertain.