In this chapter we will disco≠≠≠ver that language variation is a normal characteristic of speech on all language levels: in the sounds of accents, words, in grammar but also in discourse. When speaking, we always face alternative choices, and these are determined by our regional and social backgrounds and by the context of situation. We will discuss the concept of the sociolinguistic variable in more detail and find that variation is rule-conditioned and systematic. We focus on all actors and factors involved: the social dimension of variation (individuals, groups, communities) and its social correlates (region, class, gender, ethnicity, education). Last but not least, we will look at the spread of innovative features and trace patterns of diffusion from individual speakers, the point of origin of change, throughout wider society (via processes such as actuation, diffusion, and embedding).