The brand portfolio is the set of all brands and brand lines a particular firm offers for sale in a particular category or market segment.
The basic principle is to maximize market coverage so no potential customers are being ignored, but minimize brand overlap so brands are not competing for customer approval.
Each brand should be clearly differentiated and appealing to a sizable enough marketing segment to justify its marketing and production costs. Marketers carefully monitor brand portfolios over time to identify weak brands and kill unprofitable ones.
Brands can also play a number of specific roles as part of a portfolio.