Do you call this symbol "#" pound, hash, or number?

1) I usually call it hash or sharp in English (although # only *looks* like a sharp: ♯ ), "Raute" in German.
I just checked that its French name is "croisillon", but I guess that many would also use "diese" (♯).
It also looks a little like the Chinese character for well (井 jǐng).


2) "The well-field system (Chinese: 井田制度; pinyin: jǐngtián zhìdù) was a Chinese land distribution method since at least 9th century BC (late Western Zhou Dynasty). It is named after the Chinese character for well (井 jǐng), which looks like the # symbol and represents the theoretical appearance for a piece of land under such an organization: the eight surrounding outer blocks being private (私田; sītián), and the central one block being communal or public (公田; gōngtián)."
Source and further information:
http://en.wikipedia.org/wiki/%E4%BA%95


3) "Number sign is a name for the symbol #, which is used for a variety of purposes including the designation of a number (for example, "#1" stands for "number one"). "Number sign" is the preferred Unicode name for the code point. Its Unicode code point is U+0023, and its ASCII value is 0x23 (hexadecimal).
In most English-speaking countries outside North America, the symbol is usually called the hash mark, hash sign, or hash symbol. It is also a hash key on touch-tone phones in these areas. As used in the United States on touch-tone telephones, the key on phones is referred to as the pound key, with the symbol being called the pound sign. In Canada, this key is most frequently called the number sign key. Beginning in the 1960s, telephone engineers have attempted to coin a special name for this symbol, with variant spellings including octothorp, octothorpe, octathorp, and octatherp. None has become universal or widely accepted.

In non-English speaking nations, other names for this symbol are also used. In many parts of the world, including parts of Europe, Canada, Australia, and Russia, "number sign" is the name of the "numero" sign № (Unicode code point U+2116), which is often written simply as No. In some of those countries, the # sign is not used to indicate a number.
The symbol is easily confused with the musical symbol called sharp (♯). In both symbols, there are two pairs of parallel lines. The key difference is that the sharp has two diagonal "horizontal" strokes (that is, the horizontals are not truly horizontal in the sharp). By contrast, the number sign (#) does have two truly horizontal strokes, combined with two "vertical" strokes that may or may not be truly vertical depending on the style of typeface or handwriting."
Source and further information:
http://en.wikipedia.org/wiki/Number_sign