The document discusses the StringTokenizer class in Java, which is used to break a string into tokens. It provides three examples of how StringTokenizer can be used: [1] to print each token in a string; [2] to calculate the average of grades entered on one line; and [3] to display student IDs, number of quizzes taken, and average from a file with IDs and grades. The key StringTokenizer methods like hasMoreTokens(), nextToken(), and countTokens() are also overviewed.