This educational video lecture distinguishes between the different ways we use modal verbs to express the concept of possibility. The primary focus is the distinction between using "can" for general, typical, or common truths and using "may" or "might" for specific chances occurring in the present or future. Through a series of structured exercises and a grammatical chart, the source clarifies that while "can" describes what is generally possible for anyone, it cannot be used to guess about a particular person's immediate needs or a specific event's outcome. Ultimately, the material serves as a practical guide to help students master the nuances of impersonal versus circumstantial probability in English.