Glossary

What is BlockDAG?

A ledger where blocks can have several parents, so blocks mined at the same time all stay in.

A blockDAG (block directed acyclic graph) is a ledger structure where each new block can point back to several previous blocks, not just one.

In a blockchain like Bitcoin, each block has a single parent. If two miners find a block at the same moment, only one can be kept. The other becomes an orphan and its work is wasted. That is why Bitcoin keeps blocks slow, around one every 10 minutes, so collisions are rare.

In Kaspa's blockDAG, a new block references every tip it knows about. Parallel blocks are merged rather than discarded, which is what lets Kaspa run at 10 blocks per second without wasting honest work.

Why ordering matters

Keeping every block raises a question: if two blocks contain conflicting transactions, which comes first? A consensus protocol answers it. Kaspa uses GHOSTDAG today, with DAGKnight planned next.

Directed and acyclic

• Directed: references only point backwards in time, from a block to the blocks it builds on.
• Acyclic: you can never follow references and loop back to where you started.