This document discusses brand extensions and sub-branding. It defines line extensions as extensions within the same category, while category extensions move into a new category. Strong parent brands often lead to strong extensions. The document uses the example of Barefoot & Pregnant, a training brand for hotels, extending into virtual training for day spas. While extensions leverage parent brand equity, they can also damage the parent brand if poorly executed. The document argues that sub-branding, using a new brand name tied to the parent, can help extensions grow new market segments without risking the parent brand.