Inbound marketing works by attracting potential customers to your company website. Once they arrive, inbound tools are deployed to convert those qualified visitors into leads, and ultimately customers who will promote your brand.
Traditional outbound marketing, such as TV or radio advertising, can be an annoyance to potential customers. It's also famously inefficient. Inbound is the antidote, because with inbound your ideal customers come to you, on their own time and by their own will. That makes for happy customers.