It's a long story. Ultra shortened:

The Steemit stake (about 70 million Steem) was frozen by the witnesses after Justin Sun bought Steemit. They did this so he could not vote witnesses or posts. He then lied to Binance and Huobi and they powered up their customers' Steem to elect 20 witnesses by Justin Sun, thus he unfroze his stake. So the complete chain was temporary under his control, witnesses regained control partly. It was a stalemate, nobody could fork, negotiations didn't have any real results. Community decided to fork away, putting the Steemit stake into the DHV (Decentralized Hive Fund). And here we are.

You can use https://peakd.com/ for a better UI. Not sure how much you know about the developements on Steem, but we have Steem-Engine now, which allows for tokens, Steemit-clones with your own token and NFTs and some other stuff.

Check out https://steemapps.com/ for a list of other Steem apps. Most of them will eventually move to Hive but that will take some time, mainly because Steem-Engine will take some time to move.

Feel free to ask any questions.