iostream

#include <iostream> includes the iostream header.

It gives access to things like std::cout and std::cin.

std::cout prints data to the console:

std::cout << "Hello\n";

The << operator sends data to the output stream.

The direction of the symbols helps me remember the direction of data flow.

std::cin reads data from the keyboard:

int x {};
std::cin >> x;

std::cin does not wait for the user if there is already matching data in the buffer.

Characters not extracted by operator>> remain in the buffer for later.

For a normal newline, I should use:

'\n'

So the basic rule is:

std::cout << "Text" << '\n';

Not:

std::cout << "Text" << std::endl;

Unless I actually need a flush.