A blend of hardcore and metal music that evolved in the mid-to-late 90's with bands like Unbroken, Earth Crisis, Harvest, Endeavor, Poison The Well and Unearth. There is a liberal use of breakdowns in the music and the lyrical themes range from the political to the personal.

Often associated with the nu hardcore and fashioncore scenes.

Metalcore is a genre that has been around since the eighties but not totally popularized until the mid 90's with bands such as Unearth, the modern forerunners in the genre. It includes a mixture of hardcore punk and heavy metal and uses generally two guitarists, a bassist and double kick drums for the instrumentals. Many bands use more than one singer, one generally for more melodic lines and the other, lead singer, who carries many of the vocal burden and usually "screams".

A genre of music that had began in the late 80s/early 90s. Originally combining elements of metal and hardcore, it has now evolved into a dime-a-dozen plethora of bands that sound exactly the same. New school metalcore bands borrow heavily from melodic European death metal combined with stolen Slayer riffs and vocals ranging from annoying screams to cupped-mike growls. Band names are usually longer than the songtitles (i.e. Between The Buried And Me, Every Time I Die, etc). Mostly caters to mallrat teens who are glued to Facebook, shop at Hot Topic, wear skinny jeans, skateboard, and play Call Of Duty all day long.

a poor excuse for all metal

Shitty genre of music. It is said to be derived from hardcore punk and heavy metal, but really sounds like Panic! at the Disco with heavier guitar riffs. The vocalists are usually washed up emos.

A watered down poor excuse for a metal genre that claims to mix extreme metal and Hardcore punk but really adds Emo, Screamo, Pop and Glam as well. A sorry metal sub genre that falsifies the idea of punk metal into crappy crybaby new generation "brutal" pop metal. Emos and Scene Kids mostly listen to this type of music. Typically, Metalcore = Emo Metal & Deathcore = Scene Metal. Its a band wagon genre like Glam Metal and Rap, people fallow it to the end of its popularity and go back to listening to something usually non-metal related. But not always, sometimes they mature their Heavy Metal music tastes and find better music. Core kids often refer this type of music to Post Hardcore, the name states what it is, "WASN'T" hardcore.
Some of these bands try to label themselves as Grindcore or Thrash but are far from the idea of ever being so.

The genre has motivated a bunch of kids to start these types of bands and fill the underground scene with terrible ill-prepared wanna be in a band type music.

The term used to label two musical genres.

1) The fusion of hardcore punk and thrash metal sounding exactly like the sound of it - Integrity or Converge are good examples

2) Extreme metal, usually simplified, with emo clean singing, screamo harsh vocals and an excess of breakdowns which sound nothing like hardcore punk. A fabricated genre aimed at making money and being popular. Why is this called "metalcore" is beyond me.