During the preparation of the observing programme of the TYCHO project on board the HIPPARCOS mission we started thinking about the large number of new variable stars that would be discovered. And since the TYCHO experiment yields only a scanty number of scattered measurements of each star during the life time of the satellite, it is immediately evident that one will encounter the problem of recognising the type or class of variability to which the variable star belongs. Such classification is - even with abundant data - not a trivial task, since many variable stars have light curves which, at first sight, look very similar. In addition, proper classification needs much more than a good-looking light curve, since luminosity and effective-temperature photometric indices also play a role, as well as miscellaneous data obtained with apparatus that are complementary to photometric instruments.

We thought to get some help by looking for standard light curves of typical variable stars that would be used as a template during the process of classification. We discovered then, with some surprise, that a compilation of typical photoelectric light curves of variable stars has never been published, nor does there exist a concise compendium of photometric properties of groups and classes of variables. What can be found, instead, is a large number of detailed morphological descriptions and numerous photometrically-incompatible photographic and visual light curves, scattered over many books and journals.

So, we decided to fill this gap and we started the compilation of typical light curves in a format that enables quick recognition of the pattern of variability.