Answer: Conversing with others online in public and branded spaces.
What to call it is not really that important though, the important thing is to understand every day hundreds of millions of people are talking online about the products and services they like and the ones they are going to avoid, and you need to be engaged with these current and prospective customers and in these conversations.
More and more, buying and career decisions are increasingly being made without reference to traditional corporate websites, advertising, marketing, PR, HR and sales departments. Too, while social media seems to be moving at lightning speed, we are far from the stage of maturity and there are still plenty of opportunities for companies to learn, adopt and change.