Tilde

Tilde is the name of this diacritic:

~

Found on a(n American) keyboard on the upper left key.

Use in non-English languages

As a diacritic it appears over a letter in Spanish or Portuguese making the sound of that letter more nasal.

Use in the geeky, computery realm

A string of tildes on a wiki site like this one (Mediawiki) works in a special way.

~~~ If you put three tildes together while editing a page, when you click "save," it will automatically turn that into your username, with a link to your user page. (example: Pete F)

~~~~ Four tildes in a row has a similar function, but also adds a "date stamp" -- it inserts the current time and date. (example: Pete F 18:47, 31 May 2009 (PDT))

~~~~~ Five tildes in a row inserts just the date stamp, without specifically identifying you as the author (though that information is still preserved in the page history). (example: 18:47, 31 May 2009 (PDT))

Use as a graphical element

Used on its own, it is a swung dash and functions like a dash, but is curvier :-)