Conversational marketing is a term coined by Drift:
A one-to-one approach to marketing that companies use to shorten their sales cycle, learn about their customers, and create a more human buying experience.Drift
Following this definition, conversational marketing includes any kind of two-way engagement with prospects and customers. This kind of communication should happen preferably in real-time and with personalization in mind. Conversational marketing should be used along the whole funnel.