In sociology, a lifestyle is the way that a person (or a group) lives. This includes patterns of social relations, consumption, entertainment and dress. A lifestyle typically also reflects an individual's attitudes, values or world view. Having a specific "lifestyle" implies a conscious or unconscious choice between one set of behaviours and some other sets of behaviours.
Being a part of the BDSM or Fetish lifestyle does not mean that you share all the views, behaviours or attitudes of others in the lifestyle. There is a great deal of variety in what people under those umbrella-terms mean by it and which parts they incorporate into their own lives. 'Alternative' behaviour and practices (primarily sexual or sensual) is the main common theme between all in the lifestyle.
The word "lifestyle" apparently first appeared in 1939. Alvin Toffler predicted an explosion of lifestyles ("subcults") as diversity increases in post-industrial societies. Pre-modern societies did not require a term approaching sub-culture or lifestyle, as different ways of living were expressed as entirely different cultures, religions, ethnicities or by an oppressed minority racial group. As such, the minority culture was always seen as alien or other. Lifestyles, by comparison, are accepted or partially accepted differences within the majority culture or group. This tolerance of differentiation within a majority culture seems to be associated with modernity and capitalism.