Just to slightly elaborate on mutexe's answer, the names of these operators helped me to understand the difference and distinguish them:
>> Is called the Extraction operator, for instance: std::cin >> var;. The operator extracts a value from std::cin (standard input) and puts it into "var".
<< Is called the Insertion operator, for instance: std::cout << var;. The operator inserts the value of var into std::cout (standard output), effectively printing it on the screen.