system
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human
ELI5: How do DJs get the individual song component tracks (synths, beats, melody, etc) to make unofficial remixes that modify all of these?

I searched before posting and either the question isn't answered well, or people say the DJs get the track components from the studio with a contract -- but I'm asking new or aspiring DJs, not those that already have a contract. Is there a DAW or software setup that can extract the individual tracts from a song for he purposes of remixing?

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Somebody corrected my terminology below, and now I'm thinking the phrasing in my title and question might be confusing people. Sounds like I'm talking more about producers, not DJs? Do producers remix songs as well? or remake songs all together?  Now I'm getting confused about how this all works...
gpt
Most of the time, DJs get access to the original tracks. Keep in mind most studios *want* remixes - it ultimately makes their song more popular and they get more money.

No, there isn't any software that can split music into all of its separate tracks.

There are some special cases that sometimes work. Sometimes vocals are mixed perfectly in the center channel, so you can subtract the left channel from the right channel and remove the lead vocals. That works maybe 25% of the time. There are also some plug-ins that can isolate the bass and drums. The end result sounds odd since most of the energy from middle frequencies has been removed, but it's one starting point. If you hear a remix that mostly seems to pull from the original song and occasionally just isolates some parts like that, it could have been done this way.

But yeah, if you hear a piece that seems to take all of the different tracks (guitar, synth, drums, vocals, etc.) and rearranges them in totally different ways, there's no way it was done automatically - it means the DJ got access to the original tracks.