Make decisions in your code using if, else if, and else.
The `if...else` statement is the cornerstone of decision-making in JavaScript. It allows your program to respond differently to different situations by executing code only when a specific condition evaluates to `true`. The basic structure starts with an `if` block. The code inside this block will run if and only if the condition in the parentheses is met. You can optionally add an `else` block, which provides a default path of execution for when the `if` condition is `false`. This creates a simple binary choice. For more complex scenarios with multiple possible outcomes, you can chain conditions using `else if`. This allows you to test a series of conditions in order. The first condition that evaluates to `true` will have its corresponding code block executed, and the rest of the chain will be skipped. A final `else` block can be added to the end of the chain to catch any cases that didn't match the preceding `if` or `else if` conditions. Mastering `if...else` logic is essential for creating dynamic and responsive applications, as it allows you to handle user input, check application state, and control the flow of execution based on variable data.