A stage or phase in life - such as being single, independent and working, being a parent of young children, or being an 'empty nester' (those whose children have recently left home).
Lifestage is assumed to be linked to certain opportunities and constraints and to be significant to certain activities or choices. In addition, it is suggested that different psychological tasks have to be undertaken as the individual matures, and transitions between lifestages can be times of crisis.
In the context of qualitative market research, lifestage is often more relevant and useful for recruitment purposes than 'hard' demographics such as age, especially for group discussions. This is because people at the same lifestage generally have far more in common and will work better together than those simply of the same age.