How does exception handling work in Python?

An exception is an error that occurs during the execution of a program. Python allows catching and handling exceptions so the program doesn't crash.

try/except syntax:

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Division by zero!")

Full try/except/else/finally construct:

try:
    number = int(input("Enter a number: "))
except ValueError:
    print("That's not a number!")
else:
    # Executes if NO exception occurred
    print(f"You entered: {number}")
finally:
    # ALWAYS executes
    print("Shutting down")

Catching multiple exceptions:

try:
    value = int("abc")
except (ValueError, TypeError) as e:
    print(f"Error: {e}")

Hierarchy of main exceptions:

• BaseException
  • Exception — base class for most exceptions
    • ValueError — invalid value
    • TypeError — invalid type
    • KeyError — key not found in dictionary
    • IndexError — index out of range for a list
    • FileNotFoundError — file not found
    • ZeroDivisionError — division by zero

Important rule:

Catch specific exceptions instead of a generic except Exception — this helps avoid hiding unexpected errors.