For the purpose of better visualization, we often show electrons as point particles following a particular path, or orbit.  Such a model is often dubbed a "solar-system" model.  One should note before continuing that the concept of distinct orbits is one aspect of the solar-system model that fails to accurately represent atoms.  Instead, each electron is spread throughout a "cloud" surrounding the nuleus.  The density of the cloud at a point represents the probability of finding the electron at that particular location when a measurement is made.  For more information, try these links:

Click HERE for a nice tutorial on the quantum model of the atom, or HERE to go directly to the page describing electron clouds.  The tutorial is part of the University of Colorado's Physics 2000 project.

Click HERE for a succinct description of electron clouds from CRD Training Coporation's PhysChem site