Alpha Centauri is a triple-star system. One of the three stars in Alpha Centauri is Proxima Centauri, which is the nearest star to the Earth, except, of course, for the Sun. The name «Proxima» comes from a Latin word which means «close».
Even though Proxima Centauri is the closest star to the Earth outside of our solar system, it is not really close. Interstellar distances are so large that they are almost impossible to imagine. A person traveling in a modern spacecraft would not arrive at Proxima Centauri within this lifetime, or the next, or even ten lifetimes because the distance is so great. Light travels at a speed of 186000 miles per second, and it still takes light more than four years to travel from Proxima Centauri to the Earth.
Alpha Centauri can be easily seen in the night sky without a telescope from certain parts of the Earth. It is the third brightest star in the sky, out of approximately 6000 visible stars. It cannot be seen from most parts of the United States because most of the United States is too far north; however, it can be seen from the southern parts of the southernmost states.