What do we use to define a block of code in Python language?

In Python language, we use indentation to define a block of code. Here are the steps:

1. Start by declaring a function or a condition. This could be an if statement, a for loop, a while loop, or a function using def.

2. After the declaration, put a colon : at the end of the line.

3. On the next line, add an indentation. This is usually four spaces or one tab.

4. Write the code that you want to include in this block. As long as the code is indented, it is considered part of the same block.

5. When you want to end the block, simply stop indenting the code. The next line of code that is not indented is outside of the block.

Here is an example:

def my_function():  # Step 1 and 2
    print("Hello, World!")  # Step 3 and 4
print("Outside of the function")  # Step 5

In this example, print("Hello, World!") is inside the my_function block, and print("Outside of the function") is outside of the block.