Atheory of how consumers decide what to buy

1)The lifestyle of a consumer will influence on his behavior and purchasing decisions. For example, a consumer with a healthy and balanced lifestyle will prefer to eat organic products and go to specific grocery stores, will do some jogging regularly (and therefore will buy shoes, clothes and specific products),

2)Cultural trends or “Bandwagon effect” are defined as trends widely followed by people and which are amplified by their mere popularity and by conformity or compliance with social pressure. The more people follow a trend, the more others will want to follow it.

3)The membership groups of an individual are social groups to which he belongs and which will influence him. The membership groups are usually related to its social origin, age, place of residence, work, hobbies, leisure, etc..

I’m sorry , what i don’t comprehend

I'm pretty sure illustrators are often represented among the staff of an advertising agency