We will introduce the electrical imaging method of Electrical Impedance Tomography (EIT) from a biomedical engineering perspective. In EIT currents are introduced into the body and voltages recorded on a set of conventional surface electrodes. This information is used to reconstruct an image, however the problem is ill-posed with the number of voxels in the images several of orders of magnitude more than the number of measurements. We have made improvements with the use of internal electrodes and will some recent results in applying EIT to a range of problems in electrophysiology for cardiac and neural applications.