The US Department of Justice said Thursday that the attorney general has begun a rule-changing process that if finalized would reclassify marijuana as a schedule III drug. It's been considered a schedule I drug since the 1970s, putting it in the same federal legal class as drugs like heroin. 

Drugs are scheduled, in part, by a judgment of whether they serve a medical purpose, or how much that purpose outweighs the risk of dependence or abuse (someone becoming physically addicted or someone using a drug outside a purpose that's prescribed or allowed). In the DOJ's posted notice of the rule, the agency said it's changing marijuana's schedule because the Department of Health and Human Services has found that marijuana has accepted medical uses. 

Despite marijuana being legal in some US states for medicinal or recreational purposes, this week's announcement has been considered historic because it represents a shift away from rules many politicians and health experts have said don't align with marijuana's actual risk-benefit profile. 

What does this change mean for consumers? As of now, nothing at all. Marijuana is still illegal at the federal level, and there's a 60-day window during which members of the public can submit opinions to the Drug Enforcement Administration before the rescheduling is finalized. Some harm-reduction and medicinal-use advocates are also pushing for additional action from lawmakers that may have more impact on how people are criminalized for using or selling marijuana, and on how federal rules line up with state laws.

Here's what to know.

Is weed now legal at the federal level? 

No. Changing how marijuana is scheduled doesn't decriminalize it. Until a final rule is published, the DOJ says, marijuana remains a schedule I controlled substance. Even if its rescheduled status is finalized, that won't decriminalize or legalize marijuana at a countrywide level. 

But it is a step toward removing some of the red tape around a drug many people use, either recreationally or medicinally.

"My hope is that going forward, this is going to change the way we talk about cannabis, the way we think about cannabis, and ultimately, the way we as a country legislate cannabis," Paul Armentano, the deputy director of NORML, an advocacy group for the legalization of marijuana, said during a media briefing earlier this month. 

What medical benefits and risks are there to marijuana? 

This week's federal-level step comes on the heels of findings from the Department of Health and Human Services that conclude marijuana does have medicinal purposes, including treatment for symptoms associated with anorexia, cancer and chronic pain, particularly neuropathic pain. 

According to the US Centers for Disease Control and Prevention, pain management is one of the most common reasons people seek medical marijuana in the US. And according to GoodRx, the medicinal properties come in because the active chemicals in cannabis, called cannabinoids, interact with binding sites in the body and can turn nerve signals on and off.

The use of cannabis or marijuana has been researched for other health conditions too, including anxiety, epilepsy, glaucoma, HIV or AIDS symptoms, PTSD, some sleep problems, and more, and as a way to decrease opioid use.

Because marijuana contains the cannabinoid THC, which causes mind-altering effects, the short-term impact of it can lead to disruptions in how you sense things, your mood, and more. Some people like these feelings, which is one reason for recreational use.

As the Cleveland Clinic notes, more research on long-term marijuana use is needed. But in terms of risk, some research has linked long-term marijuana use to gum disease and problems with sperm development, which can impact fertility. Other research has linked marijuana use to lung problems and to increased risk of vascular disease. 

Frequent marijuana use has also been linked to a higher risk of developing schizophrenia or psychosis in people who are predisposed, according to the clinic. Using marijuana at a young age has also been linked to cognitive effects, with impacts on attention and learning.