Cables have three main parts. They have two ends, with appropriate connectors depending on the use, and the wire that runs between them. Cables are typically male/male such as 1/4 TRS cables or male/female such as microphone (XLR cables).
XLR's are typically microphone cables. They can also be used to connect to a direct box which covers those 1/4 inch guitar cables into XLR cables for feeding into a stage snake or floor box. One end of an XLR is male and the other female.
XLR's can be strung together in low impedance settings. For most stage uses, one XLR cable should be long enough for any job.
XLR's are composed of three wires; a ground and two signal wires (hot/cold). XLR's are balanced cables so outside noise that might get into the wire is eliminated when the signal is converted.
RCA Phono Connectors:
RCA connectors are usually thought of as home audio cables. However, these cables can still be seen in live sound environments. Usually they are plugged into stereo converters before being plugged into an audio mixer / console.
RCA cables aren't meant for heavy use. They are meant to be plugged in and left alone forever.
RCA connectors themselves can easily become loose and difficult to keep plugged in when used over and over.
1/4 inch Connectors:
There are two types of 1/4 wires; balanced and unbalanced. The balanced cables (TRS for tip, ring, sleeve) have two rings on the connector while the unbalanced only has one. The unbalanced wires (TS for tip, ring) are usually used for guitars and keyboards.
There are combo connectors that work for both XLR and 1/4 inch cables. As the world can be a crazy place, you will find many non-standard cable connectors on the market. Lucky for most of us, we don't see those in the everyday environment.
Some cables don't have the same types of connectors on opposite ends. This is usually because the jack on a piece of equipment doesn't match the type that is required to plug into something else.
Gold Plated Connectors:
Gold plated connectors are used because gold doesn't tarnish and therefore better consistent electrical contact. This can be useful for all non-moveable audio components. However, because it is gold "plating," any frequent plugging and unplugging could quickly wear away the gold plating.
Thought? Questions? Comments?