The If Statement

In programming, we don't always want every line of code to run. Sometimes, we only want an action to happen if a specific condition is met. This is called conditional logic. At the heart of this is the Boolean value, which can only be $True$ or $False$. When you write an `if` statement, Python checks the condition. If the condition evaluates to $True$, the code inside the block runs. If it is $False$, Python simply skips over it and moves to the next part of the program. It is like a gatekeeper that only opens the door when the password is correct.

To write an `if` statement, you must follow Python's strict syntax rules. First, you start with the keyword `if`, followed by your condition (like $x > 5$). Second, you must place a colon `:` at the end of that line. This colon acts like a signal saying, 'The instructions are coming up next!' Finally, the code that belongs to the `if` statement must be indented (usually 4 spaces). This indentation is how Python knows which lines are part of the decision and which lines are just the rest of the program.

When reading code, you must act like the computer. Look at the variable values first, then solve the math in the condition. If the condition is $False$, ignore everything indented. For example, if we have `age = 10` and the code says `if age >= 18:`, the computer sees $10 \ge 18$ as $False$. It will skip the indented block entirely. This 'skipping' is what allows programs to behave differently in different situations, making your software feel 'smart' and responsive to user input.