Active Listening and Observation is probably my most important skill! Arguably, it's one of the most important social skills anyone can have.
Active Listening is mostly about listening to understand, but not necessarily to respond. Active Observation provides the context for what someone is saying.
In addition to listening, it's also critical to observe the many clues that we all give each other by the way we present ourselves, body language, and even what we don't say.
This skill is not natural, as most of us listen primarily to respond. That's not necessarily bad because normal conversation requires back-and-forth communications.
Why it's especially important for a consultant to be expert at Active Listening and Observation is that they are responsible for gathering data from people that they may have little or no relationship with and using that data to create a business result. They are frequently doing so in a stressful situation or high-stakes environment. Failure to truly understand the client and the team creates a high risk for project failure.