The education industry, meaning colleges and universities, need a way to "add on" additional skill emphasis to degrees without requiring whole new degrees.
They are called graduate certificates. You take a couple of graduate level courses, and you get a graduate certificate. Often, you can get a certificate while you are on the path towards a masters.
Or, if you don't need a piece of paper, you can just find classes that interest you, and take them.
Where I work, tuition reimbursement exists if you are enrolled in a degree or certificate program -- it's much harder to get the company to pay for a single class. For that reason alone, graduate certificates are great.