How does Kaspa's DAG structure prevent double spending?

Kaspa prevents double spending by ordering all blocks in the DAG and including only transactions that do not contradict earlier ones. In a traditional single-chain blockchain, each block points to exactly one previous block, creating a strict line. Kaspa instead uses a DAG — a directed acyclic graph — where a block can point to many other blocks at once. Once the DAG is traversed and ordered, any transaction that would spend the same coins twice is identified and excluded, because it contradicts a transaction already accepted earlier in the ordering. This ordering mechanism is the core of the GHOSTDAG protocol. For a beginner, the practical takeaway is that Kaspa's DAG lets many blocks exist in parallel without opening the door to fraud, because the ordering rules close that gap automatically.