[from the mainstream meaning and 'Binary digIT']
n. 1. [techspeak] The unit of information; the amount of information obtained by asking a yes-or-no question for which the two outcomes are equally probable.
2. [techspeak] A computational quantity that can take on one of two values, such as true and false or 0 and 1.
3. A mental flag: a reminder that something should be done eventually. "I have a bit set for you." (I haven't seen you for a while, and I'm supposed to tell or ask you something.)
4. More generally, a (possibly incorrect) mental state of belief. "I have a bit set that says that you were the last guy to hack on EMACS." (Meaning " think you were the last guy to hack on EMACS, and what I am about to say is predicated on this, so please stop me if this isn't true.")
"I just need one bit from you" is a polite way of indicating that you intend only a short interruption for a question that can presumably be answered yes or no.
A bit is said to be 'set' if its value is true or 1, and 'reset' or 'clear' if its value is false or 0. One speaks of setting and clearing bits. To toggle or 'invert' a bit is to change it, either from 0 to 1 or from 1 to 0.