Plans the flight, and shares legal responsibility for it with the captain.

In much of the world a dispatcher is jointly responsible with the captain for the decision to operate. They build the flight plan, choose the fuel, pick the alternates, and stay with the flight while it is airborne, rerouting it around weather and finding it somewhere to go when its destination closes. It is a licensed role and almost nobody outside the industry knows it exists.
A few months full time, then a licence check ride. No degree required.
Airlines often sponsor the course for people already working in ops or load control.
No published projectionDispatchers are counted by the Bureau under a broader transportation-worker heading with no published outlook of its own, and the Occupational Outlook Handbook has no entry for the role. Rather than borrow the controllers’ numbers, which are a different job with a different licence, this profile quotes none.
A bad weather day is eight hours of decisions with real money and real safety on each one, and you cannot leave the desk. Shifts cover the whole clock. Almost nobody outside the industry understands what you do, including, at first, your family.