Despite the seething turmoil of the Sun's surface, our daytime star's output of energy is very steady. This is very fortunate for us but many of the stars visible to the naked eye, and thousands within the range of binoculars or a moderate telescope, markedly change their brightnesses. Some change erratically. Some are very predictable. Others may be fairly predictable but can sometimes spring surprises on the observer. Noticeable changes can take years to occur or, in some cases, just minutes.

In many ways these variable stars are just as individual as people, each with its own characteristics. However, astronomers have classified these stars into a number of types, the behaviour of the members of each type being broadly similar. Adopting a number of variables to observe and periodically estimating their brightnesses is a very positive way of communing with our Galaxy at large. It is also a very scientifically valuable exercise. Most of the panels of astronomers that allocate observing time on professional telescopes, allow individuals or groups a few nights each to follow up some specific project. Here the amateur, with his/her telescope on hand whenever the sky is clear, scores heavily over the professional.

Though some professional astronomers are doing observational work in this field, an amateur observing group's records, for instance those of the BAA Variable Star Section or the American Association of Variable Star Observers (AAVSO) are often called upon by researchers.