The theory of Feynman diagram is proposed and invented by American Physicist Richard Feynman (1918 – 1988). He introduced to world his diagram in 1948 and for his path breaking work he received the Noble prize. According to him these diagrams can be used in quantum Physics and in solid state theory. Richard was among among one of the world’s top 10 scientists by a poll conducted in the year 1999. He was member of the team which invented first atomic bomb of Modern world and also the panel member of the team which investigated the space shuttle challenger disaster. For representing the complex equation governing the interaction of the sub atomic particle, Feynman Diagrams are used. It’s easy to understand the diagrammatic representation than analysing the equation. The Feynman Diagram gives a visual explanation of the complex scientific representation. . The Feynman Diagrams have been shown as the space diagrams with the space as one axis and time as another. The space axis is right axis as shown and the time axis is upward axis. Moreover the space axis is similar to x axis and time axis is similar to y axis of the Cartesian co-ordinate system . . In the above diagram, an electron enters and it either emits a photon or absorbs a photon and exits. The photon is shown as the wave in the diagram. The arrow indicates the path taken by the particles. The exchange, emission or absorption of photon occurs at the vertex as shown above. . There’s few things to remember when analysing the Feynman diagram. The particles are denoted by the solid lines with the arrow pointing in the direction of travel. The antiparticles on the other hand are another denoted by the solid lines however the arrow in their case is reversed. The virtual particles, like photons, are represented either by the wavy or broken line as shown in the diagram above . Consider the above diagram. Two electrons (or like charges) interacting with each other. The result is the exchange of energy (via a photon particle) . .