Some good examples of post-hardcore are:
From Autumn to Ashes
My Chemical Romance (on their first album)
Haste the Day
Post-hardcore contains elements of hardcore, punk, and metal, with slightly heavy, fast-paced guitar riffs. Screaming is the main vocal feature, but there are also melodic breakdowns sung in clean vocals at other times, usually in a fairly high voice.
The lyrics are often regarded as what people believe as "emo" nowadays, but if emo really did stand for "emotional", then practically all music out there should be called emo as well, like Britney Spears. The real emo is actually very different compared to the emo that MTV brainwashed everyone with, but I won't go into depth about that because there are plenty of entries of emo that talk about the real deal.
A lot of people like to associate modern post-hardcore with emo and screamo, especially since some post-hardcore bands selected those as their genres on their Myspace, but that is because Myspace doesn't have anything near post-hardcore as a selection, so selecting emo and screamo are probably the only other closest genres that people would familiarize with post-hardcore (although the real emo and screamo aren't very similar to modern post-hardcore at all). Please don't call post-hardcore "emo" and "screamo". It's post-hardcore.
Funeral For A Friend (before Tales Don't Tell Themselves)
A Skylit Drive
Escape The Fate
Before Their Eyes
Eyes Set To Kill
I Am Ghost
Bear Vs. Shark
The Rites of Spring
and, of couse, At The Drive-In.
Some post hardcore bands:
-a skylit drive
-Behind Crimson Eyes (good aussie band)
-Drop Dead, Gorgeous
-Escape The Fate
-The Fall of Troy (experimental)
-From Autumn to Ashes
-The getaway plan (good aussie band)
-Protest the Hero
-Story of the Year
Some hardcore/Metalcore bands:
-Bring Me the Horizon
-Destroy the Runner
-Haste the Day
-I Killed The Prom Queen (aussie hardcore, GETSOME!)
-Parkway Drive (aussie hardcore)
post hardcore kid: *round house kick*
The Washington, DC scene surrounding Dischord records circa 1985 is often considered ground zero for post-hardcore, thanks largely to Revolution Summer, a campaign by Dischord to revitalize the then-creatively stagnant Washington, DC hardcore punk scene. Initially, groups like Embrace, Rites of Spring and Ignition integrated melody, a sense of groove, an introspective lyrical focus, and a stronger command of rock songwriting into hardcore sensibilities, though subsequent groups formed circa 1987 such as Moss Icon and Soulside moved post-hardcore into a more art rock direction by introducing elements such dynamic shifts, progressive songwriting styles, and angular guitar work influenced by the original post-punk movement, in many ways the sonic and spiritual antecedent of post-hardcore.
Fugazi, formed in the late 1980s by former members of Embrace and Rites of Spring, were arguably the most important and influential post-hardcore band. Committed to independent rock values, touring throughout the world, and relentlessly pioneering stylistically, Fugazi played throughout the 1990s and set the tone for the American underground rock scene during that time. By the start of the new millennium, post-hardcore groups like At The Drive-In, Unwound, Les Savy Fav and the Dismemberment Plan had all released sonically lush albums, landed major label contracts, or both. Additionally post-hardcore had also arrived as a force in popular culture by that time under the guise of emo, for better or worse. Sadly, post-hardcore's current state is one of confusion and dilapidation, as many pedestrian emo groups have adopted the term as representative of their style in hopes of increasing their credibility.