A breaker that trips once in a while during a thunderstorm is usually nothing. A breaker that trips daily is telling you something is wrong.
Overloaded circuit: too many high-draw appliances (AC, iron, water heater) on one circuit. Fix: redistribute load across circuits — not dangerous, but inconvenient.
Short circuit: a hot wire touching a neutral or ground wire. This trips the breaker instantly and repeatedly. This is dangerous and should not be reset repeatedly without inspection.
Ground fault: current leaking to ground, often from damaged wire insulation or a faulty appliance. Also a safety risk, especially in bathrooms and kitchens.
A worn-out breaker: breakers degrade over 15-20 years and can trip even on normal load. Simple replacement.
If your breaker trips immediately every time you reset it, stop resetting it and get an electrician to check for a short circuit before using that circuit again.