In Dart, the `main()` function serves as the entry point of a Dart program. It is the function that is executed when the program starts running. The `main()` function is mandatory in every Dart program and is typically the first function that gets executed.

Here are the key points regarding the `main()` function:

1. Function Signature : The `main()` function has a specific signature: it must be defined as a top-level function and have a return type of `void`. It does not accept any arguments.

   void main() {
     // Program execution starts here
   }​

2. Execution Start : When a Dart program is executed, the code inside the `main()` function is executed sequentially. It acts as the starting point of the program's execution.

3. Top-Level Function : The `main()` function must be defined at the top level of the Dart program, meaning it cannot be defined inside another function, class, or any other block of code.

4. Program Termination : The `main()` function acts as the last executed code block in the program. Once the execution of the `main()` function completes, the program terminates.

The `main()` function allows you to define the initial logic of your Dart program. You can use it to call other functions, instantiate objects, perform calculations, handle user input, or execute any other code that needs to be executed when the program starts running. It provides a centralized location where the program's execution begins and allows you to structure and organize your code effectively.