Begging the question is a straight-forward fallacy, that I was about a second away from making in my post on Kant. It happens when your conclusion is in essence provided in one of your premises.
Major premise: Women are discriminated against in the workplace.
Minor premise: Women earn less than men.
Conclusion: Women earn less because they are discriminated against.
In this case, the conclusion is contained fully in the major premise and is thus a case of begging the question. It is one of those fallacies that is very hard to catch in a debate simply because by the time you have had enough time to process it, the speaker will have moved on.