All T cell functions require establishing contacts with other cells. In the last ten years, the immunological synapse, the contact-site between T cells and their partners, has been the object of numerous investigations and recent advances in imaging technologies have provided significant insights into the mechanism of immunological synapse formation and its functional outcomes. Considering all the available data, the immunological synapse can be defined as a dynamic structure, formed between a T cell and one or more antigen-presenting cells, showing lipid and protein segregation, signaling compartmentalization, and bidirectional information exchange though soluble and membrane-bound transmitters. In this review, we present the current views on the immunological synapse and discuss about some interesting unresolved questions.