The pound sign (£) is the symbol for the pound sterling--the currency of the United Kingdom and previously of Great Britain and the Kingdom of England. The same symbol is used for similarly named currencies, such as the Gibraltar pound, the Egyptian pound, the Syrian pound, etc. It is also sometimes used for currencies named lira, for example the now withdrawn Italian lira.
The symbol derives from a capital "L", representing libra pondo, the basic unit of weight in the Roman Empire, which in turn is derived from the Latin word, libra, meaning scales or a balance. The pound became an English unit of weight and in England became defined as the tower pound (equivalent to 350 grams) of fine (pure) silver. According to the Royal Mint Museum:
It is not known for certain when the horizontal line or lines, which indicate an abbreviation, first came to be drawn through the L. However, there is in the Bank of England Museum a cheque dated 7 January 1661 with a clearly discernible £ sign. By the time the Bank was founded in 1694 the £ sign was in common use.
However, the simple letter L, in lower or upper case, was used to represent the pound sterling in printed books and newspapers until well into the 19th century.
The symbol ? (note the double dash at its middle) was called the lira sign in Italy, before the adoption of the euro. It was used (in free variation with £) as an alternative to the more usual L. or Lit. to show prices in lire. It was also used unofficially as the symbol of the Maltese lira instead of the official Lm.
In American English, the term "pound sign" usually refers to the symbol #, and the corresponding telephone key is called the "pound key". In Canadian English the symbols £ and # are both called the pound sign, but the # is also referred to as the "number sign" and the "noughts-and-crosses board".
In the Unicode standard, the symbol £ is called "pound sign" and the symbol ? "lira sign". These have respective code points:
Some fonts render the pound sign with a double bar (for example on a previous version of the British five pound note); this is simply a different glyph, and the underlying character (and therefore Unicode codepoint) is still a pound sign, and not a lira sign.
The encoding of the £ symbol in position xA3 was standardised by Latin-1 in 1985. Position xA3 was used by the Digital Equipment Corporation VT220 terminal, the Amstrad CPC, the Commodore Amiga and the Acorn Archimedes. The IBM PC originally used a non-standard 8-bit character set Code page 437 in which the £ symbol was encoded as x9C; adoption of ISO character codes only came later with Microsoft Windows. The Atari ST also used position x9C. The HP Laserjet used position xBA for the £ symbol, while most other printers used x9C.
The BBC Ceefax system which dated from 1976 encoded the £ as x23. Many early computers used a variant of ASCII with one of the less-frequently used characters replaced with the £. The UK national variant of ISO 646 was standardised as BS 4730 in 1985. This code was identical to ASCII except for two characters: x23 encoded "£" instead of "#", while x7E encoded "?" instead of "~". The ZX Spectrum and the BBC Micro used x60 ("`"). The Commodore 64 used x5C ("\") and the Oric used x5F ("_").
IBM's EBCDIC code page 037 uses xB1 for the £ while code page 285 uses x5B. ICL's 1900-series mainframes used a six-bit encoding for characters, loosely based on BS 4730, with the £ symbol represented as octal 23 (hex 13).
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Typewriters produced for the British market included a "£" sign from the earliest days, though its position varied widely. A 1921 advertisement for an Imperial Typewriters model D, for example shows a machine with two modifier shifts (CAPS and FIG), with the "£" sign occupying the FIG shift position on the key for letter "B". But the advertisement notes that "We make special keyboards containing symbols, fractions, signs, etc., for the peculiar needs of Engineers, Builders, Architects, Chemists, Scientists, etc., or any staple trade."
On Latin-alphabet typewriters lacking a "£" symbol type element, a reasonable approximation could be made by typing an "f" over an "L".
In the punched card era, equipment sold for commercial data processing in the UK needed not only to represent the pound sign, but also to handle pre-decimal currency (pounds, shillings, and pence, including halfpennies and farthings).
On a US-International keyboard in Windows, the "£" can be entered using:
On a US-International keyboard in Linux and Unix, the "£" can be entered using:
In Windows, it can also be generated through the Alt keycodes:
On UK Apple Mac keyboards, this is reversed, with the "£" symbol on the number 3 key, typed using:
The compose key sequence is:
Until 2017 the logo of the UK Independence Party, a British political party, was based on the pound sign, symbolising the party's opposition to adoption of the Euro and to the European Union generally.
A symbol that appears to be a pound sign is used as the logo of the British record label Parlophone, in fact this is a Germanic letter L standing for Lindstrom (the firm's founder Carl Lindstrom) and harking back to the companies roots as a Berlin based maker of gramophones.