Modals in English Grammar
In the country of verbs, 'modals' is one of its states where its population are special kinds of verbs. They have their own rules and behave differently.
What Are Modals and Semi-modals?
Modal verbs (also called modals or modal auxiliary verbs), are special verbs that give additional information about the function of the main verb that follows them. Modals have a wide variety of communicative functions (i.e. modality).
Some verbs share only some of the characteristics of the modals. These verbs are called semi-modals (or pseudo-modals or quasi-modals).