The Supreme Court on Tuesday heard arguments about the legality of broadcast TV streaming operator Aereo. The case pits traditional television broadcasters against Aereo, which lets customers record broadcast TV in their local markets and then watch programs via television, computer, tablet or smartphone.

Q. What is Aereo?

A. Aereo, which was founded in 2012, is a service that lets paying subscribers watch broadcast TV on smart phones, tablets and computers. The company builds “antenna farms” that are filled with DVRs and thousands of dime-sized antennas. Using the Internet, customers can tune in and record local affiliates.

Q. Sounds complicated?  Was it for the justices?

A. Most of the justices displayed a decent understanding of technology, actually. Justice Sotomayor revealed she has a Roku, for instance. Other justices invoked Dropbox and Netflix. There were some exceptions, however. Justice Breyer made a few dated references to record stores – that is, stores that sell phonograph records.

Q. What does the case hinge on?

A. Under copyright law, there is a distinction between private performances and public performances of copyrighted works. Private performances are legal. You could invite friends over to your house to watch a basketball game, for instance. Public performances are illegal.

Aereo stresses each subscriber has a one-to-one relationship with its technology – DVRs and antennas. Each customer has total control over each of those two things. Broadcasters argue that, because Aereo has thousands of customers, what it is doing is illegal.