A "phasor" is a vector.
When these vectors are represented on the paper we obtain a phasor diagram.

See,
http://www.kwantlen.ca/science/physics/faculty/mcoombes/P242...
Phasor Diagrams. In AC electrical theory every power source supplies a voltage that is either a sine wave of one particular frequency or can be considered ... Phasor Diagrams. It is sometimes helpful to treat the phase as if it defined a vector in a plane. The usual reference for zero phase is taken to be the ...

http://info.ee.surrey.ac.uk/Teaching/Courses/ee1.cct/circuit...
The phasor diagram • Phasor diagrams and impedances • Phasor diagrams and series circuits • Phasor diagram and parallel circuits ...

http://www.physclips.unsw.edu.au/jw/AC.html
Here's where phasor diagrams are going to save us a lot of work. ... Phasor diagrams in RMS have the same shape as those drawn using amplitudes, ...

http://www.ux1.eiu.edu/~cfadd/1160/Ch22AC/RCL2.html
We can understand AC circuits in terms of phasor diagrams. Here a vector of length Vo rotates with angular velocity . Its projection onto the vertical axis ...

http://commons.wikimedia.org/wiki/Category:Phasor_diagrams_f...
In electrical engineering phasor diagrams are used to visualize complex constants and variables phasors. The diagram shows a sine wave whose ...