This is what Bluegrass means to me: Bill Monroe, Flatt and Scruggs, Jim & Jesse, the late Chubby Wise, Doyle Lawson and Quicksilver, etc., weekends listening to professional and semi-professional bands on stage beneath a canopy of trees and dinner on the ground, or on stage in a hotel ballroom; jammin' with other bluegrassers who do take their music and techniques serious, but can laugh at themselves when they don't get it right; a basic band has a BANJO (gotta have a banjo if you're gonna call it Bluegrass), GUITAR (and I've always thought a flatpick was just a guitar and a flatpicker and guitar player), FIDDLE (a player who knows how to improvise and rock his bow); a MANDOLIN (this adds life and interest to the band), and an UPRIGHT BASS. All of these instruments are acoustic, including the bass. Too many bands use electrified bass even when all the other instruments are acoustic. For many years the Kansas Bluegrass Assoc. would not allow an electrified bass on stage, but some of the professionals use it because it's easier to travel with.
But most of all, which I haven't seen mentioned here is the gospel part of bluegrass. Bill Monroe, the "father of bluegrass" started singing in the church choir, then progressed to forming a band, and gospel remained a large part of his repetoire during his lifetime. Doyle Lawson also grew up with gospel and it is still very much a part of his programming--and I've never heard anyone perform gospel like Lawson does. For me, bluegrass isn't real unless it includes gospel. That's why there are so many nice folks in bluegrass, ya know. They know gospel and live it. I hope that part of bluegrass is never, ever lost.
Many of the people I know that play bluegrass can't read a note of music and play everything by ear which encouraged improvisation. But there are also many who have been trained classically, and sometimes you can't tell the difference. It's all in how hard the person works at it and rather or not they get over their shyness to risks of improvisation. And I know some kids who pick it up and are playing practically all the instruments in a few years time. Another thing I love about bluegrass is the informality that goes along with performing and jamming. Slapstick and comedy can be a part of it, and I'm talking clean comedy. It's all very entertaining and relaxing. As you can see I love it.
I play bass and I think it's the easiest instrument to play. Plus, it being so easy, I can play and enjoy the talents of the other pickers or let my mind drift to watching people or kids or nature. Ahhhhh, heaven!