1. They use different figures of speech, like a rhyme, direct speech… He tells about the mistic event mad by the common people or animal. Moreover, the employ the simple language, hence we can say that the ballads below are the popular poem written by the folk. In particular, Ballads tells about many aspect of Middle Ages’ culture, which are religion (“The three ravens”), love (“The Unquiet Grave”) and supernatural (“The wife of Usher’s Well”).
2. The two aspects underlined by the ballads are love and death. The first one is presented following the courtesy culture. Indeed, in “The unquiet grave” the man would do anything to kiss his dead lover. 

However, death is in every ballad. It is not presented like the end. Indeed, in “The three ravens” and “The wife of Usher’s Well” death is associated to the Christian vision, hence the dead go to the heaven or to the hell. In “The unquiet grave” the idea of death is presented in different way. Death becomes a long sleep.