sustain

What is all the talk about sustain? Sustain is the ability of a note to continue ringing, right? Unless your playing whole notes at 50 BPM, why do you need a note to sustain so long? Please enlighten me, thanks.

Ok, it may seem like an odd question, but I am wondering if using in ear monitors (IEMs) has the effect of decreaseing sustain. Follow me a bit. With an acoustic guitar, often they can feedback by the PA causing the strings to vibrate, which starts a cycle of string vibrating, and the pay...

I've owned a 4-string frettless Corvette for about a year now and I get a great sustained "muwah" sound from the E A and D strings, but the G string just doesn't sustain very well. The sound just dies out. Could it be related to the height of the string and/or relief of the neck?