Tris (One of the few chemicals we go through in buckets)

Tris is one of the most common buffers out there and absolutely ubiquitous in molecular biology. The idea behind a buffer is that you have a compound that takes on a proton (hydrogen) at a certain pH, usually somewhere near neutrality, you have about half with and half without a proton, and you have a solution held near that pH. Tris buffers a shade above pH 8, which is a little basic, but not so bad. It's pretty transparent to UV light, water soluble, and cheap. The last is probably the big thing; we have a paint-bucket sized container of tris in the lab. It's probably the only compound I dispense with a big ol' scoop.

For reasons that are in part historical, tris is ubiquitous in DNA electrophoresis - "gels." Not to say that some people suggest other things. The two most common electrophoresis buffers are TAE (tris-acetate-EDTA) and TBE (tris-borate-EDTA); these people suggest that just borate is plenty (and faster and better, as the brand name would indicate). I've tried using the borate-only buffers with not much luck (but apparently they're not good for the larger DNAs I was trying to characterize). Post all your gel buffer rants below.