Introduction to the 555 Timer IC

The 555 Timer IC was introduced by a company called Signetics (later bought out by Philips) in 1972 and was designed by Hans R. Camenzind in 1971. The 555 chip has 25 transistors, 15 resistors and 2 diodes in an 8 pin DIP (Dual In-line Package) and looks like a square bug with eight legs. It has a notch at the top and Pin 1 is in the top left corner.
http://www.instructables.com/file/FED4KHEH5IRV0NI
(Source: http://en.wikipedia.org/wiki/File:Signetics_NE555N.JPG)