The "-ed" ending is commonly used in English to form the past tense of regular verbs. When a verb is regular, adding "-ed" to its base form indicates that the action has already happened. For example, the verb play becomes played, showing that the action of playing occurred in the past. In addition to forming the past tense, "-ed" can also create past participles, which are used in perfect tenses and passive voice. For instance, the verb finish becomes finished, which can be used in sentences like "I have finished my homework." This helps convey completed actions in relation to the present.