What Is Control Flow?
When you write code, the computer doesn't just randomly pick which lines to execute. It follows a specific path through your program — this path is called control flow. Understanding control flow is essential because it determines what your program actually does.
By default, code runs sequentially — line 1, then line 2, then line 3, straight down the file. This is the simplest form of control flow. But sequential execution alone would make programs incredibly limited. Imagine a calculator that could only add, or a game that played exactly the same way every time.
Beyond Sequential Execution
Real programs need to make decisions and repeat actions. This is where control flow gets interesting:
Branching lets your program skip certain lines based on conditions. "If the user is logged in, show their dashboard. Otherwise, show the login page." The program takes different paths depending on the situation.
Looping lets your program repeat lines multiple times. "For each item in the shopping cart, calculate the price." Instead of writing the same code a hundred times, you write it once and let the loop handle repetition.
Most programs combine all three — sequential execution, branching, and looping — to create complex behavior from simple building blocks.
A Recipe Analogy
Think of a recipe. Most steps are sequential: chop the onions, heat the oil, add the onions to the pan. But recipes also have conditionals: "If the dough is too sticky, add more flour." And they have loops: "Stir every 30 seconds until the sauce thickens."
Your code works the same way. The default is to proceed step by step, but you can branch based on conditions and loop to repeat actions.
Why This Matters
Control flow is what makes programs interactive and useful. Without conditionals, programs couldn't respond to user input. Without loops, programs couldn't process lists of data. Every app you use — from social media to banking — relies heavily on control flow to function.
In the following lessons, you'll learn the specific syntax for conditionals and loops. But first, it helps to see the big picture: you're learning to direct traffic through your code.