Recently, someone asked me again what "data availability / ordering / finality" really means.

I’ll focus on one main point: at the moment you interact, does it count as "really written in," and can others mess up the order afterward?
Data availability means not just seeing "a hash on the chain," but that the data can be retrieved and re-verified by everyone;
Ordering is whether your transaction gets stuck in a queue, front-run, suffer from slippage, or get sandwiched—those are the most frustrating;
Finality is whether a transaction shows success today but gets rolled back tomorrow—something like airdrop tasks that are especially afraid of this.

Honestly, I see myself more as someone watching the checklist during night shifts rather than an academic studying terminology.
Recently, with some places tightening and loosening taxes and compliance, and deposit/withdrawal expectations fluctuating, I’ve become more anxious:
Rules change, but the chain doesn’t—people’s behavior will change…
First, make sure the interaction is on a "publicly accessible, sufficiently confirmed" data layer, and then worry about the rest.