Have you tried the official website to find information about this project? In general, it is quite popular, recently it was in the second place of the largest blockchain networks.
I would argue with you that this network is the second largest. But in terms of prospects, the project is really very interesting. And there is not much information on the official site.
This network is very popular, the development of this network began a long time ago in 2015, about the same time and started the development of etherium. Vitaly Buterin and Gavin Wood started developing this project together. You can read when did polkadot launch on this website. You can find a lot of information here about this project. Including what other projects have been created within this network.