A sequencer is the component of a layer-2 network that receives users' transactions, puts them in order, executes them and posts the results in batches to the base chain (Ethereum, in Robinhood Chain's case).
Why ordering matters to traders
Whoever controls ordering controls who gets filled first. On Ethereum mainnet, users can pay higher fees to be included sooner, which opens the door to front-running and sandwich attacks. Many layer 2s instead run a single sequencer with a fixed ordering rule.
Robinhood Chain's approach
Robinhood Chain's documentation says transaction order is decided by arrival time at the sequencer, not by gas fees. That is first-come, first-served sequencing. Paying more gas doesn't move you ahead in the queue.
Educational content only. Not financial advice.