Marketing trick.
If you want electricity to pass between two pieces of metal that are just in physical contact with each other (not bolted or soldered or welded etc), of everything we know of, pure gold is the best, it has the lowest contact resistance and it maintains the lowest contact resistance if it is unplugged and replugged and unplugged, etc.
Obviously, gold is expensive but we learned a long time ago that, if you do it right, a thin layer of electroplated gold is just as good as solid gold.
One common problem occurs when someone, usually the business managers who are focused on profits and who do not understand the physics (and don't listen to their engineers who do understand the physics) decide to use thinner and thinner layers of gold. A very very thin layer can, if you're careful, work ok once but, with repeated use, you need a gold layer that is thick enough.
Gold is the best material for conductivity (reason why it is used on computers) and there is the side advantage of being corrosion resistent. The only problem is the high cost, so platting is used, instead of using only gold.
To provide a reliable contact because no oxide film forms on gold as it does on most other metals. Metal oxides normally either do not conduct or do not conduct very well.
Silver and copper are actually better conductors than gold but they are subject to the formation of such oxide coatings which impair the contact quality.
Gold is a good conductor and a passive metal
Better electrical connection and will not corrode.
Some examples are HDMI cords, headphone jacks, etc. What's the purpose?
