1. execution process in Python

1. Briefly explain the execution process of a Python file?

🧭 Step-by-Step Execution Process of a Python File:

1. Read the Source Code (.py file)

   • Python reads your .py file line by line.

2. Lexing and Parsing

   • The interpreter breaks the code into tokens (lexing) and builds an internal representation (AST – Abstract Syntax Tree).

3. Compilation to Bytecode

   • Python compiles the parsed code into bytecode — a low-level, platform-independent set of instructions.
   • This bytecode is usually stored in .pyc files inside the __pycache__ directory for reuse.

4. Interpretation by the Python Virtual Machine (PVM)

   • The PVM executes the bytecode line by line.
   • This is where actual program execution happens — variables are stored, functions are called, etc.

🧠 Visual Summary:

.py file (source code)
    ↓
Lexer & Parser
    ↓
Abstract Syntax Tree (AST)
    ↓
Bytecode (.pyc)
    ↓
Python Virtual Machine (PVM)
    ↓
Output / Runtime Behavior

Example:

def greet():
    print("Hello")

greet()

• Parsed into AST → compiled to bytecode → executed by the PVM → prints "Hello".