Heusler compounds were discovered by Fritz Heusler more than century ago and are still a field of active research. Novel properties and potential areas of applications emerge with time; recently the prediction of topological insulators is one of the example. Their electronic structure is very flexible which allows the realization of multiple contradictory functionalities within one ternary compound. Multifunctional properties based devices such as superconductivity and topological edge states has revolutionized technological applications. Heusler compounds having semiconducting properties are utilized for the development of novel materials for energy technologies. Their band gaps can easily be tuned from zero to 4eV by changing the chemical composition, so they find lot of applications in the fields of thermoelectrics and solar cell research. Heusler compounds have wide range of multifunctional properties reflected in extraordinary magneto-optical, magnetoelectronic, and magnetocaloric properties. The most prominent example is the combination of magnetism and exceptional transport properties in spintronic devices. Here we take a review of the crystal structure, the electronic structure and the relation to the magnetic properties.