what is armature

An armature is a part of motor which allows the flow of induced emf, which produces because of flux produced by the field winding( a field winding is one in which we apply the line) due to which there is a flow of current this current tries to oppose is cause as stated by the lenz's law.
An armature winding may be placed on the rotor or the stator,so it can be rotating as well as stationary . For example-
In induction ,dc motor armature winding is in the rotor,while in synchronous motor armature winding is stationary and the field winding is rotating.