Screamo is a genre of music which predominantly evolved from hardcore punk, among other genres, in the early 1990s. The term "screamo" was initially applied to a more aggressive offshoot of emo that developed in San Diego in 1991, which used short songs that grafted "spastic intensity to willfully experimental dissonance and dynamics."
In the early 2000s media, including music channels like MTV, magazines and numerous websites picked up the genre name and started labeling any band that uses screamed vocals as a screamo band. This common misconception leads people to falsely believe that many post-hardcore and alternative rock influenced pop rock bands like Alesana and Escape the Fate are screamo bands when in reality those bands have nothing in any way to do with the music genre. So now in pop culture the genre name is described as a completely different style of music by people who don't know what screamo actually is. The real screamo scene didn't change and is still active to this day all over the world.