Modal verbs are used to indicate modality such as likelihood, ability, permission, and obligation. The modal verbs covered in the document are could, managed to, can, will be able to, may/might/could, must, can't, should, must, and have to. These modal verbs are used to talk about ability and achievement in the past and future, possibility and certainty, advice and obligation, and past modality. Examples are provided to illustrate the usage of each modal verb.