cin in c++
The "cin" is a standard input stream, used to accept input from the standard input device, which is usually the keyboard.
When you write "cin >> variableName;", it means to input a value from the user through the standard input and store it in the variable "variableName".
For example:
int number;
cin >> number;
This code will prompt the user to input a value, and then store that value in the variable "number".