ACID HOUSE TO TRIP HOP.

A rave is generally an all-night party featuring nonstop, beat-heavy electronic dance music. Anything goes, often from lollipops and nutrient-enriched ``smart drinks'' to drugs such as LSD and ecstasy.

One of the original attractions when raves started in the late '80s was that they were held illegally, often in abandoned warehouses, and advertising was done through fliers.

There are multiple categories of rave/techno/house music, most of which are rapidly melting into and borrowing from one another. Further variations include trip hop, hard hop, trip house, house beat, acid jungle and acid house.

House: Supposedly originated in Chicago, where DJs combined Kraftwerk and soul records with a drum machine.

Acid house: The next step, when drum machines and synthesizers started producing a more liquid sound.

Techno: The beat, usually 115 to 160 per minute, is used as a hypnotic tool. Proto techno includes everything from minimalist industrial technopop to party-time funk and the addition of hip-hop to form electro. Detroit techno is stripped down, with an aggressive funk sound and pounding rhythms. Hardcore techno incorporates speed-metal and industrial sounds. Techno/rave is softer and more accessible and is far more likely to include vocals.

Breakbeat: Uses high-speed samples of hip-hop and sometimes reggae at 130-160 beats per minute. The genre includes jungle, which borrows from reggae, and darkside, eerie music in minor keys sometimes including sci-fi samples.

Ambient/ambient house: More soothing music with an almost new-age feel.

Trance: Similar to ambient and acid house, it's softer but still fast enough to dance to.

Tribal: Incorporates rhythm patterns and sounds of world music.

Progressive: Based more on live instruments and less on samples, sometimes resembling acid jazz.

Deep house: Wailing divas and organs appear on this mix of gospel and old-fashioned Chicago house music.

MEMO: Source: Based on ``The Official alt.rave FAQ'' at http://www.hyperreal.com.