We use the “def” keyword to define functions in Python because it is a reserved word that tells Python that we are defining a function. The syntax for defining a function in Python using the “def” keyword is as follows:
def function_name(parameters):
function_body
Here, “function_name” is the name of the function, and “parameters” is a comma-separated list of input parameters that the function expects. The “function_body” is a block of code that defines what the function does.
By using the def keyword, we are able to define functions in Python that can be reused in different parts of our code, making it more modular, maintainable and reusable. Defining a function allows us to package a block of code into a single unit that we can call from other parts of our code, with different input parameters.