Electric fields contain electrical energy with energy density proportional to the square of the field intensity. Electric fields exist around all charges; the direction of field lines at a point is defined by the direction of the electric force exerted on a positive test charge placed at that point. The strength of the field is defined by the ratio of the electric force on a charge at a point to the magnitude of the charge placed at that point. In the dynamic case the electric field is accompanied by a magnetic field, by a flow of energy, and by real photons.
The concept of electric field was introduced by Michael Faraday .
The electric field or electric field intensity is a vector quantity, and the electric field strength is the magnitude of this vector.
For more details see 
- Learning by Simulations Interactive simulation of an electric field of up to four point charges
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