Can someone please explain to me why people perceive different colours on this dress?

So supposedly this trended a few years ago, but I only saw it for the first time today. When I look at the photo, I perceive the dress to be BLUE and BLACK. I then asked six other people, two of whom saw the same colours as I did, while the others saw it as WHITE and GOLD.

I would appreciate it if you could tell me which colour combination you see, and if someone can explain the cause of this discrepancy to me, I would be thankful.