Its a person who likes hardcore/happy hardcore/early-rave music, the word gabber originates from the dutch word that means 'friend'. The whole scene also originates from holland especially rotterdam. The gabber was born in the early ninetees with early rave music. Most gabbers don't have too much hair on their head and prefer to wear tracksuits. Most 'real' gabbers use drugs frequently (especially xtc).
There is one specific gabber dance which is called "hakken".(if u wanna see some wannabe's 'hak', google it)
These days the gabber scene still lives on but in a different way.
The music became tougher. The most popular events these days are thunderdome and masters of hardcore. Popular Dj's are Dj Paul/promo/angerfist/tommyknocker and alot more dutch/italian dj's.
Some misunderstandings are around that the gabbers are rascists but a gabber is all about the music and having fun going out.
The music has nothing to do with nazism or anything related to that, sure there are exceptations but there are exceptations in everything.
Man , that was an insane gabber party!
Those gabbers sure know how to have fun!