Nxt/Ardor can be seen as an agile, base-layer protocol upon which developers without much prior knowledge in the cryptocurrency field can create a large range of secure decentralized services, apps, and even new currencies. With Smart Transactions Ardor/Nxt do not require script processing or transaction input/output processing on the part of network nodes; scripts are already embedded, the code which is executed is actual software that runs in the node server.
Lior Yaffe, 2016. Bitcoin vs. Nxt, PoS vs. PoW, Nxt vs. Ardor.
Nxt / Ignis' use of ‘Smart Transactions’.
Nxt / Ignis transactions do not require script processing or transaction input/output processing on the part of network nodes; scripts are already embedded, the code which is executed is actual software that runs in the node server;
When a user wants to express their opinion at a poll, purchase an item in the marketplace or sell some stocks, the transaction the user submits contains only the parameters necessary for the transaction, and the ID of the functionality they want to use, keeping the consensus of the majority of the nodes as the absolute proof that the output, saved in the next block, is the genuine result of that transaction. A computer application has tenfold more power and possibilities, compared to a script interpreted in a virtual machine, as it is the case with the “smart contracts” used in f.x. the Ethereum blockchain.
Ignis Lightweight Contracts offer a way to deploy turing complete Java contracts onto a proven PoS blockchain network.
Read the articles
Lior Yaffe about developing and using Lightweight Contracts.
Nxt / Ardor Stateless Contracts vs. Ethereum's "Smart" Contracts.
^ Thorough documentation and helpful screenshots to aid anyone in the installation and usage of Ardor's advanced Lightweight Contracts functionality. Contracts and unit tests have been developed to support your learning experience.
Lior Yaffe elaborates on the theme of Lightweight Contracts
You can buy NXT, IGNIS, and ARDR with fiat and cryptocurrencies like BTC and ETH. By keeping your tokens on a centralized exchange, you leave them to the owners of that exchange to control. Beware.