Cosmos sdk first question

Hi I am new to cosmos, when I started appd in local, does it connect to other validators in cosmos network or I have to establish the network by myself with others running the same appd? try to compare it with ethereum

Cosmos philosophy is “application specific blockchains”. So each blockchain needs to put together its own validator set. What people often refer to as the “cosmos network” and “cosmos validator” is the particular blockchain known as “Gaia” or the “Cosmos Hub”, which is the blockchain that hosts the Atom token. There’s lots of other cosmos blockchains like Kava and Terra and Irisnet and Binance DEX and so on, but they each have their own validator set.

In the future, there will be a mechanism to bootstrap a new chain by borrowing security from existing validators on another chain, but that doesnt exist yet.

You can also checkout, which I believe is trying to help address the problem of bootstrapping new/dev chains.