Abstract
In software product-line development (SPLD), variability management plays an essential role, and multiple variability modeling methods have been proposed. Along with gradual acceptance of SPLD and diversifications of the usage of variability models, there have been proposed various enhancements on these models. In this tutorial paper, we focus on feature model, a representative variability model. We firstly introduce the original feature model and some extensions made on the model, and then introduce how these models are used in SPLD activities.