Abstract
An overview of pulsations and instabilities throughout the HR diagram
will be presented in relation to a description of the main phases of stellar evolution.
The various groups of variable stars will be discussed as well as their properties.
We shall also examine the basic physics of stellar pulsations, with a particular
emphasis on the driving mechanisms. These mechanisms are essentially effects
due to stellar opacity and radiation pressure. Radiation also plays a major role in
producing stellar winds and the many consequences of these winds on the evolution
will be illustrated.