Where are the fuses in a breaker box?

Excuse me, could you possibly provide some clarification on the location of the fuses within a breaker box? I'm attempting to understand the proper placement and accessibility of these components for maintenance and safety purposes. Is there a standard or universal area where they are typically found, or does it vary based on the specific model or make of the breaker box? Additionally, are there any precautions or steps that one should take when inspecting or replacing fuses in a breaker box to ensure personal safety? Thank you for your time and assistance in this matter.