I’m not able to understand how cin works.

That's alright. Let me break it down simply.

When writing programs, we often need to take input from the user. For example, if we want to ask for a name and then greet the user, we need a way to get that input.

In C++, we use cin to take input and store it in a variable. Here’s how it works:

#include 
using namespace std;

int main() {
    string name;

    cout << "Enter your name: ";

    // Take user's name as input
    // Store user's name in name variable
    cin >> name;

    // Greet user
    cout << "Hello, " << name;

    return 0;
}

If you run this program, you'll get this as output:

Enter your name: 

Now, you need to click on the output and enter your name. Suppose you enter John:

Enter you name: John

Now, cin >> name; stores "John" in the name variable.

Finally, cout << "Hello, " << name; prints:

Hello, John

The thing to note here is that you need to use >> when using cin and << when using cout. Otherwise, you may get an error.