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Crypto is always stored on the blockchains (on networks of servers that are on the internet)

Cryptos are never stored in centralised exchanges, and they are never stored in software or hardware wallets like ledger, metamask, trustwallet, exodus etc.

The only thing stored in the ledger is your 24 word recovery seed phrase, which is your key to access your crypto accounts on the blockchains. The ledger prevents your key to ever touch the internet or a computer, unlike software wallets that are vulnerable to malware.

Some front-ends, like metamask, can connect to the ledger, so they can use the ledger device to sagely sign your transactions with your keys.