The concept of engagement marketing is easy to understand. You contact clients and customers who already know about you, engaging with them. It involves sending them something that encourages interaction, through e-mail, one of the myriad social networks, or in some other way. Getting them to respond to you creates social visibility. It places your brand in front of them in their social network. When they respond to you, their friends see it, creating an implied recommendation for these friends to check out your products and services.