Can anyone please tell me what happens in a drug treatment program?

It seems like a handful people I know, or am acquainted with, are going to undergo drug treatment programs. I don't really know how these programs can help them. And why do they take so long? Enlighten me, please?

: http://alcoholdrugstreatment.info/can-anyone-please-tell-me-what-happens-in-a-drug-treatment-program