Nowadays, e-voting is used in more and more countries and in all kind of elections. There’s not a single solution to e-voting and each has different characteristics and areas of application. In this article we give a brief description of what we understand by e-voting systems and we introduce the different models used in remote electronic voting. We explain how these systems work and give some ideas of their advantages and drawbacks. Finally we give some examples of elections using e-voting and some ideas of the challenges that researchers try to overcome.