Speaker cable connectors? What exactly do they do?

Bare copper will oxidize over time. Oxidation is a real problem. It will rob
you of signal over the entire spectrum. You can use bare wire and simply
snip off the ends every once in awhile, trying to snip them before oxidation
becomes a problem. Connectors, if they're applied correctly and if they are
plated with a material that won't oxidize -- like gold -- can provide a better
seal and help fight oxidation. Banana plugs make it much easier to connect
and disconnect your speaker cables. Spades are a tad less convenient. Some
people say they can hear the difference between spades and bananas,
between connectors and no connectors. I usually take claims of super human
hearing with a grain of salt, but that's just me. If you think you can hear the
difference, take a blindfold test and see if you really can or if you're just
kidding yourself. Then, proceed based on your results.

But how does adding connectors to the end of the cables keep the copper from oxidizing?

Alo, the connector itself is plated with a material that resists or does not oxidize, such as gold. The site of the connection itself is typically sealed (a rubberized shrink wrap) so that no bare wire is exposed to the air. Air is needed for oxidization to occur.

Thanks for the replies. Guess i shouldn't feel too low budget for using bare wires. If I do move up to connectors, I'm assuming I'll be able to tell which ones actually cover the ends.