【转】HTML中常见形如number;的东西叫做 字符实体引用，简称引用，代表一个对应的unicode字符

英文解释的很清楚，就不翻译了，自己看：

Entities

Character entity references, or entities for short, provide a method of entering characters that cannot be expressed in the document’s character encoding or that cannot easily be entered on a keyboard. Entities are case-sensitive and take the form &name;. Examples of entities include © for the copyright symbol and Α for the Greek capital letter alpha.

In addition to entities, authors can use numeric character references. While entities are limited to a subset of Unicode characters, numeric character references can specify any character. Numeric character references may be given in decimal or hexadecimal, though browser support is stronger for decimal references. Decimal references are of the form number; while hexadecimal references take the case-insensitive form number;. Examples of numeric character references include © or © for the copyright symbol, Α or Α for the Greek capital letter alpha, and ا or ا for the Arabic letter alef.

The following documents feature tables of the character entity references in HTML 4, along with the numeric character reference in decimal and hexadecimal. A rendering of each character reference is provided so that users may check their browsers’ compliance.

下面这几个链接，包括了对应的那些字符所对应的实体引用：

下面摘录一些常见的：Character< xmlnamespace prefix ="o" ns ="urn:schemas-microsoft-com:office:office" />EntityDecimalHexRendering in Your Browser

EntityDecimalHex

no-break space = non-breaking space   

cent sign¢¢¢???

pound sign£££???

currency sign¤¤¤¤¤¤

yen sign = yuan sign¥¥¥???

section sign§§§§§§

diaeresis = spacing diaeresis¨¨¨¨¨¨

copyright sign©©©???

registered sign = registered trade mark sign®®®???

degree sign°°°°°°

plus-minus sign = plus-or-minus sign±±±±±±

acute accent = spacing acute´´´???

micro signµµµ???

pilcrow sign = paragraph sign¶¶¶???

middle dot = Georgian comma = Greek middle dot······

masculine ordinal indicatorººº???

right-pointing double angle quotation mark = right pointing guillemet»»»???

vulgar fraction one quarter = fraction one quarter¼¼¼???

vulgar fraction one half = fraction one half½½½???

vulgar fraction three quarters = fraction three quarters¾¾¾???

inverted question mark = turned question mark¿¿¿???

multiplication sign××××××

Latin capital letter O with stroke = Latin capital letter O slashØØØ???

Latin small letter sharp s = ess-zedßßß???

division sign÷÷÷÷÷÷

Latin small letter o with stroke = Latin small letter o slashøøø???

quotation mark = APL quote"""“““

ampersand&&&&&&

less-than sign<<<<<<

greater-than sign>>>>>>