Post-Emo Indie Rock is a subgenre of Emotive Hardcore (a genre that combines Indie Rock with Hardcore Punk).
In the post-emo indie rock style of Emotive Hardcore, there are a number of defining musical characteristics. The dynamics are usually focused around the extremes; alternating between loud and soft. Vocally, the singers in this style of music usually sing very softly and include very little screaming as compared to other hardcore genres. Many emo bands' lead singers often have out of key vocal melodies, earning them both praise for their originality and criticism for their strange dissonance. As this style developed, the bands began to use catchier guitar licks, centered around major-key arpeggios, while the drum and percussion parts became more controlled and light.
The subgenre of music that is classified today by some as "post-emo indie rock" was first developed in the Colorado with bands like Christie Front Drive and Boy's Life and Seattle with bands like Sunny Day Real Estate. The trend soon spread all over the Midwest, garnering the term Midwest Emo. In Chicago, Illinois around the same time, the band Gauge came out who would influence bands from their area like Braid and Cap'n Jazz who would become known as pioneers of this subgenre. A few years after Gauge broke up, the band Cap'n Jazz was experimenting, taking emotive hardcore and hardcore punk music and adding characteristics of experimental rock, indie rock, and pop rock. The trend, after exploding through the midwest, reached New York.
Bands like Texas is the Reason and Rainer Maria spearheaded the movement, and on Long Island, Inside and Garden Variety were known to take the Midwest Emo formula made famous by bands like Mineral and Sunny Day Real Estate and make it their own.
The genre for the most part has since died off during the early 2000s.