I've always wondered if this is just a marketing thing, but all across the electronic supply spectrum I see "gold plated" listed as the best conductors for various contacts and connectors. However, silver is considered the most conductive element (6.2×107 S/m), followed by copper (5.9×107 S/m), with gold (4.5×107 S/m) being third. I get that any of those are better conductors than the most common (tin and steel) but I would think silver, being less expensive, more abundant, and a better conductor, would be preferred over gold. What am I missing here?
Gold is used for connectors not so much for its conductivity as it's chemical inertness.
Even ostensibly corrosion resistant materials like aluminium and stainless steel form a thin metal oxide layer on the surface, indeed this is what gives them their corrosion resistance and metal oxides have poor conductivity.
So gold plating is potentially useful for improving the electrical connection between two contacts it tends to be most useful in signal or data connections where you are usually dealing with low voltages and maintaining a consistent resistance across connections is important.
The downside of gold is that it is soft and so prone to wear and so you tend to see it most often in connectors which need to be physically small and aren't subject to a lot of wear eg things like SIM cards, flash cards, graphics cards, phone batteries etc etc.
Where connections are changed frequently eg in music, sound and lighting equipment chrome plating or nickel plating is usually preferred as it is much harder and you can mitigate any small increase in resistance by having a larger contact area.
While gold has a slightly higher resistance, it has the major advantage of not corroding or at least corroding very very slowly in normal conditions which is why it is used for so many contacts on our day to day devices...
Silver and copper tarnish and corrode easily in the atmosphere leading to poor connections.