Directed acyclic graph
DAG, distributed acyclic graph, is a distributed-ledger technology that links transactions together directly without miners or blocks.
Currently (January 2018) there are three major DAG-based cryptocurrencies: Byteball, IOTA, and Raiblocks.
There is a wiki article comparing Byteball and IOTA.
Here is a table detailing differences among them. See the Cryptocurrency subreddit thread for further discussion.
|Address reuse||Yes||Not after sending||Yes|
|Chain type||Main chain DAG||PoW DAG||dPoS DAG+Blockchain|
|Confirmation time (theoretical)||30 seconds||Instant||Instant|
|Confirmation time (current)||~10 minutes?||Minutes to hours, to a day||~10 seconds|
- Comparison of IOTA and Raiblocks
- Wikipedia DAG article