B2C marketing, or "business to consumer" marketing, includes all the marketing actions that aim individual consumers. This is often what is meant when "marketing" is used in the broadest sense.
B2C marketing is made of the practices, actions and marketing campaigns most visible and best known and identified by the general public.
B2C marketing differs from B2B marketing which is less visible and less known, even if B2B marketing is the basis for the vast majority of trade.
To go further, see B2B marketing.