The Meaning of Life, the Universe, and Everything.
Personally I back mine up in an organised fashion before I install a mod or something. I just copy the bin and saves folders to an different folder =0 If I install a pre-release, I back up the entire .minecraft folder, just to be sure.
But what about you? Do you back up your Minecraft folders and if so, how?
Yep for mods too, but not only that, i have my .minecraft of 1.7.3
You know , like , instead of what many people do ( make 100 threads about how 1.0.0 sucks ) i just " install " my 1.7.3 jar and i play on 1.7 if i wish to do so.
For the mods, its a bit complicated.
I love to play some mods but i dont want to play every mod i have with the others, i have a .jar with 3 mods , then another .jar with other 3 mods and i install and uninstall them when i feel like i want to play the other, it is just more organized , atleast for me , i dont like to have a jar with like 20 mods that i want to play but i dont want all them together.