ED is the abbreviation of Ending Song. Its Japanese name is エンディング歌. There is also a less popular name called ending theme song or cartoon ending song, which refers to the song played at the end of the animation.

OP is the abbreviation of Opening Theme/Song, which is the opening song.

Generally, one set of OP and ED is replaced every quarter (13 episodes). But if the total number of episodes is only 13 or less, most will not change it. In a set of animations, if the number of EDs is more than one song, it will be expressed as ED1, ED2,... etc. in subsequent releases of original sound CDs, online discussions, and animation data collection. According to statistics, there are often more EDs than OPs.

Theme song (Theme) or Theme Song (Tome Song) is the main music or song used to represent the work in movies, TV series, animations, stage plays and other works.

Extended information:

If the number is more than one song, the original sound CD and animation data will be released as OP1, OP2 or the theme song (opening song). , theme song (opening song) two... etc. to express.

The title song of some works will display information such as the original author or screenwriter, director, producer, sponsor, title song songwriter, and singer. Some works that do not have an ending theme will add scripts, voice actors or actors (so some have a 2 minute and 30 second opening theme like One Piece).