Do you have a reference to a thread that discusses it in a complex way? I want to know more, I'm sure here I can get deeper insight than just reading in news outlets about crypto.
There definitely are forum threads that delve deeper into this. While I cannot point you to a specific thread at this time, I think a simple search function or Google might get you started.
In the simplest terms, cold wallets are those that never connect online directly. Most often, they are in the form of an external hardware device that is used to store the private keys of your wallet and sign transactions. But they cannot broadcast signed transactions. For that you will need the associated software or a hot wallet.