Help me out here: what is bladder infection?

Irritating: Irritation of the inner lining of the bladder. A large number of bacteria in the urine can cause the immune system to ramp up its defenses in the bladder. This will lead to irritation of the bladder. An irritated bladder is not fun. The bladder may become very active and cause frequent urination, burning, make you feel like you have to go right now, etc.

Bacterial infection: Bladder infections are usually bacterial and treatable with antibiotics after addressing the underlying cause. Women get more bladder infections than men. More during pregnancy, some related to sex. In men enlarged prostate predisposes to bladder infections. Bladder stones facilitate infections.