It's the white belt.
Stick with me here. Your white belt is the most important belt, for a lot of reasons.
Getting your white belt signifies your commitment to start something new, even though it's hard and awkward and smelly and sweaty and weird. You've bought in. You got a gi, and got to tie that belt that represents so much possibility around your waist. You are now one of us. Welcome to the fold.
Your instructor will be thrilled to get to teach another brand new person about Brazilian Jiu Jitsu, and his/her philosophies about the style of BJJ that they teach and why. There is another member of the team on the mats every night. You, young white belt, you get to help carry this on, and be part of something larger than yourself.
That white belt represents opportunities for upper belts to open up and practice new sweeps or submissions. That white belt means you can be forgiven nearly any BJJ faux pas. Don't go biting anyone, though - there's no coming back from that.
Comments disparaging white belts (fresh meat, anyone?) are not the way to foster a team, or to recognize how important that white belt is to the academy. We all need white belts. White belts are the best practice for the "anything could happen" side of BJJ. White belts aren't interchangeable. They have homes and families and jobs and hobbies, and they are choosing to take time away from those things to learn from the upper belts, to become part of this community.
We colored belts need to remember this, and welcome them (even when they break the "rules" that they don't even know yet). Help them. Make them better. Teach them how to counter your best move. This is how you get better, too.
Instructors, when you get a new white belt, I suggest tying it on your new student with as much fanfare as you have when you award a colored belt. White belts matter. Make them a priority at your academy, and your other students will also make them a priority. Invest in these new students, even though we all know what the dropout rates are like. I'd posit that these dropout rates would decline if we made getting your white belt a bigger deal than it is, and we stopped thinking of white belts as second class citizens.
On a slightly related note, I would love to see some buddy system / mentoring system for new students. The buddy doesn't have to do anything but be a little more advanced, and commit to coming to class when the new student will be there and answer their questions about gym etiquette, etc.
I know, all of you white belts (and former white belts) all think that your next belt is the important one. The secret is, they're all important. They're all the most important one. But, if you never put that white belt on, none of the rest of them matter.