The document discusses the differences between using "will" and "be going to" to talk about the future. "Be going to" is used for future plans that are already decided or predicted events. "Will" and "shall" indicate offers, promises, predictions, suggestions, and future facts that may be less certain. The present continuous can also refer to future arrangements or plans. Overall, "be going to" and the present continuous imply certainty, while "will" allows for some uncertainty which can be clarified using "probably."