What exactly is a seed phrase? Or an HD wallet?

In this video, I explain how a seed phrase is converted to a "master key" for your crypto-wallet, and why as long as you have your seed phrase (and no one else does) you can use it to set up and use a wallet on any device.

This is what non-custodial wallets are all about - your seed phrase is the key to accessing and controlling your blockchain addresses, and hence your digital assets (crypto, NFTs, or other) and ultimately your identity on the blockchain.

Anywhere, without any one else being able to block you.

Provided you're careful with that seed phrase.