Proxima Centauri is currently the nearest star to the solar system, some 4.2 light years away. There is still considerable debate whether it is a member of the alpha centauri system or not, but at this time, most observers consider that it is a member. Proxima is a red dwarf, main sequence star, and one of the faintest known, with an absolute magnitude of around 17. It is also a flare star, undergoing sudden outbursts in brightest of about a magnitude. These flares usually last only a few minutes.
Red dwarf stars are by far the most common type of star in the galaxy. However because of their faintness, they are only visible if they are relatively close to the Earth. They are also have the longest lifetimes of all stars. Proxima with still be shining steadily, albeit feebly, long after our Sun becomes a white dwarf!