At a scientific conference in Seattle on Tuesday, researchers reckoned with a day that many thought might never arrive. A patient appears to have been cured of H.I.V., the virus that causes AIDS, for only the second time since the epidemic began.

A sort of electric hope hangs in the air, said Dr. Steve Deeks, an AIDS specialist at the University of California, San Francisco, who is attending the gathering: “The whole approach to a cure is shifting more from aspiration to something that people are realizing could be feasible.”

It is a hope that must be tempered with realism: H.I.V. is a wily adversary, and scientists and patients living with the virus are all too well acquainted with past failures in the fight against the epidemic.

Here’s what the news means right now.

Will this change anything for people living with H.I.V.?

Not yet. The second case does provide “proof of concept,” shining a light on a potential path to an H.I.V. cure. Scientists intend to pursue it with vigor.