**[Dirac's Delta function][1]**

It was introduced by 1927 by Paul Dirac.
Can be regarded as an important example towards the theory of [distribution][2].

For examples of distributions to keep in mind see [this question][3].


  [1]: http://en.wikipedia.org/wiki/Dirac_delta
  [2]: http://en.wikipedia.org/wiki/Distribution_(mathematics)
  [3]: http://mathoverflow.net/questions/4706/what-examples-of-distributions-should-i-keep-in-mind