Polkadot

Kusama

Kusama is an independent network not an Polkadot testnet. They have common testnet like rococo for parachains and westend for testing the latest metadata, extrinsics etc. https://wiki.polkadot.network/docs/maintain-networks#test-networks

---

dev-discussions ⁠watercooler substrate.stackexchange.com

also we have a heroes program, a community driven learning based initiative at ⁠heroes-introduction. check channel description or ping @ zsofi_m for clarification regarding heroes program

Let me know if you need more clarification, wiki.polkadot.network has all the info you need 🙂 might as well check there

Parathread

Technically they are the same as parachains but differ from the latter by the economic model.

Parathreads use a pay as you go model and pay for each block to be validated by the relay chain

That is during times of high network congestion para threads can become quite expensive to use and during times of low activity the fees on them are low.

The polkadot network can hold up to 10,000 Parathreads

Substrate

The polkadot network itself was built by using substrate, but building parachains using substrate is not at all a prerequisite and vice versa. Blockchains with substrate can exist on their own without connecting to polkadot or kusama