system
Given the following post, respond as if you're commenting on Reddit:
human
What the hell is B-theory?

I dont even...
gpt
There's the B-theory of time which is contrasted with the A-theory.

According to the B-theory, events are ordered by relations that don't make mention of tensed terms like past, present, or future. The relations just talk about what events were before or after others.

e.g. 10/7/13 is two days after 10/5/13.

According to A-theory, relations make mention of tensed features. 

e.g. 10/7/13 is two days in the future.

The terminology was invented by McTaggert in his argument against the reality of time. He argued that the A-theory was incoherent because all events will have to have all the temporal properties since all events are future and will eventually be past. He also denies that you can solve the problem by saying that the events have these properties *at different times* because that would require another set of temporal relations and would thus just push the problem off rather than resolving it.