I've been diving into this for a long time, but I still can't help but say a few words: don't be scared by terms like "data availability / ordering / finality." Basically, there's one main point — the transaction you see, is it truly visible to everyone, is it recorded in the same order, and can it ultimately be changed? Recently, cross-chain bridges have been hacked again, or oracles report outrageous prices, and then the whole network starts "waiting for confirmation." These all serve as reminders of the same thing: the system's most vulnerable point is often not the chain itself, but "who gets to decide first, who can earn everyone's trust." Reflecting on my own recent mistakes, the first step isn't to curse my shaky hands, but to ask: which "final" layer did I actually trust at that moment? Let's start here, and don't get carried away by the rhythm of new narratives again.