The initial interaction between a virus and its target cell drive the cell tropism of the virus, and is the primary target of the immune response. The entry of enveloped viruses into cell occurs into two steps, the binding and the fusion of the envelope with the cell membrane. The binding requires the recognition of a virus ligand by a cellular receptor. The fusion involves a fusion protein, and in some cases, a secondary interaction of the virus ligand with a cellular coreceptor. Despite a large structural diversity of cellular (co)receptors, virus ligands and fusion proteins, the increasing amount of molecular data allows to build a common model describing the entry of an enveloped virus into a cell. A better knowledge of the underlying molecular mechanisms could unravel new therapeutic approaches such as the emerging anti-virus virus.