what was so relevant about it that it has been trending for a week?
sorry if this an obvious thing for USA folks, but I have honestly no idea what that service was.
I upvoted because I think the replies to this thread will be valuable.
538, named for the combined number of senators, representatives, and electors in the US, was a political journalism site. It used polls and data to ground its articles and opinions. Largely helmed by Nate Silver for a large portion of its run, until he left.
It got 49/50 states correct in the 2008 presidential election which catapulted it to fame. It never scored that accurately again but it's data driven charts and tables were a great pulse point for US politics. You could see recent aggregated polling data day by day in the run up to an election. And you could read analyses of polling data and trends.
There's nothing like it anymore, it didn't make money and didn't make spot on predictions reliably. It didn't need to do either, it was a good pool of data at the end of the day.
Everyone seems to rely on Polymarket now, which is a much more cynical way to aggregate polling data - by betting on predictions.